Julian Assange, the founder of WikiLeaks, received a hero’s welcome even before he was set to arrive back in his home country of Australia on Wednesday after pleading guilty to a felony charge of violating the U.S. Espionage Act.

Australian politicians sprinted to publish statements supporting a plea deal that gained him his freedom. Kevin Rudd, the former prime minister who is now Australia’s ambassador to the United States, even joined him in the U.S. courtroom on the Pacific island of Saipan.

That Mr. Assange’s case concluded in a distant outpost — the capital of the Northern Mariana Islands, a commonwealth tied to America through post-World War II imperialism — seemed fitting.

He ended his standoff with the American government far from Washington, 14 years after he published classified military and diplomatic documents, revealing secret details about U.S. spycraft and the killing of civilians during the wars in Iraq and Afghanistan.

He was a divisive figure then — a brave journalist to some, a reckless anarchist who endangered Americans to others. He became even more polarizing during the 2016 presidential election, when WikiLeaks published thousands of emails from Hillary Clinton’s campaign and from the Democratic National Committee that had been stolen by Russian hackers.

But after five years in a British prison, and marriage and fatherhood, Mr. Assange had turned into a figure more appealing for Australians. Somewhere along the way, he became the underdog forced to endure superpower pique, and in a land settled by convicts, a rebellious bloke who had done his time and deserved to return home.

Prime Minister Anthony Albanese of Australia said the court proceedings that freed Mr. Assange were “a welcome development.”

“This is something that has been considered, patient, worked through in a calibrated way, which is how Australia conducts ourselves internationally,” he said Wednesday.

“Regardless of what your views about Mr. Assange’s activities,” he added, “his case has dragged on for too long.”

Critics saw a lack of introspection in that response. It ignored that Australia’s own espionage laws are some of the toughest in the democratic world, with punishments stretching to 25 years in prison and weak protections for journalism. And it sidestepped the Albanese administration’s continued resistance to granting greater transparency with public records and the failure to strengthen whistle-blower protection laws, despite frustration over several secretive cases.

Johan Lidberg, an associate professor of journalism at Monash University in Melbourne who has worked with the United Nations on global press freedom, said he was surprised by the broad political support for Mr. Assange. He had somehow unified, for a moment, Greens and Labor lawmakers along with conservative leaders. But how?

Mr. Lidberg said sympathy for Mr. Assange started to build in Australia after 2016, when at the urging of President Trump, he was dragged out of the Ecuadorean Embassy and put into Belmarsh, a prison in southeast London.

“His case went from one of hacking, journalism, publishing, advocacy to becoming a humanitarian issue,” he said. “It could be that the Australian myth of ‘the fair go’ played a role. It was seen that he didn’t get a fair go, and was mistreated.”

The desire to protect accountability journalism — a factor for many Americans who worried that a conviction for Mr. Assange would send a threatening message to reporters and sources — was not a major concern in Australia, where there is no constitutional right to free speech.

James Curran, a history professor at the University of Sydney and an international affairs columnist, said Australians do not necessarily share the same kind of reverence as Americans do for “the whole culture of secrecy and classified documents.”

When a bipartisan group of Australian politicians went to Washington to lobby for Mr. Assange in October, they did not stress the need to protect the Fourth Estate.

“They emphasized how China and Russia are using the Assange case as proof of blatant Western hypocrisy when it comes to the handling of political prisoners,” Mr. Curran said. “This did cut through in Washington.”

American law-and-order had already lost some respect. Many Australians now harbor whispered disapproval for the U.S. criminal justice system, which they see as too performative and punitive, with capital punishment in some states and long prison sentences in most.

“It is the high rates of incarceration, the abuse of the plea-bargaining process, even the conduct of U.S. police,” said Hugh White, a former Australian defense official and now a professor of strategic studies at the Australian National University. “I think even quite conservative people doubted the Assange would ‘get a fair go’ at the hands of the D.O.J.”

Last year, when Secretary of State Antony J. Blinken visited Australia for high-level defense talks in Brisbane, he was asked about Mr. Assange’s case — and bristled at the idea that Mr. Assange was a victim of American capriciousness.

Standing at an outdoor lectern, flanked by military veterans, Mr. Blinken said he understood “the concerns and views of Australians” but that it was “very important that our friends here” understood Mr. Assange’s “alleged role in one of the largest compromises of classified information in the history of our country.”

His comments sounded defensive to many Australians, and condescending. Australia and America are still shoulder-to-shoulder allies, having fought together in past wars, and they are now building a framework of collective defense to deter potential Chinese aggression. But Mr. Blinken’s tone helped make Mr. Assange a proxy for another element of the Australian relationship to the United States: An abiding ambivalence about the idea of American exceptionalism.

“In part this is just a reflection of the ambivalence that great powers always engender among their smaller satellites, but it is not just that,” Mr. White said.

Among conservative, Anglo-centric Australians, there is also some resentment about America displacing the British Empire after World War II, he added. Others have felt that the United States has often been too quick to dismiss the concerns of its friends, and by continuing to prosecute Mr. Assange, “the U.S. has looked unreasonably vindictive,” he said.

Getting the United States to back down — and listen with a bit more humility — seems to be what Australian politicians are eager to celebrate. Along with Mr. Albanese, rural conservative lawmakers and Greens party liberals also praised Mr. Assange’s release. Mr. Rudd smiled enough during his own appearance in court to be mistaken for a defense lawyer.

Their mood of victory, however, may yet fade. Will the next round of leaks reveal secrets about Australia? What if Mr. Assange and WikiLeaks choose a side in the U.S. election or war in Ukraine that most Australians do not support?

“The case can be made that WikiLeaks helped Trump and Putin more than anybody else, and put lives at risk,” Mr. Curran said. “This seems not to have really sunk in to the Australian debate.”