President Trump is the last person in America with standing to complain about suppression of free speech. This is the candidate who lustily encouraged the roughing up of protesters at his 2016 rallies. This is the president who has called journalists whose work fact-checked his lies or challenged his party line “enemies of the American people” and threatened to use the power of government to go after the business interests of CNN and the Washington Post.

So it was with no deficiency of audacity that Trump last weekend suggested he was about to issue an executive order to pull federal aid from colleges and universities that do not sufficiently guarantee free speech for diverse viewpoints.

His pledge in a rambling two-hour speech to the Conservative Political Action Conference drew rousing applause. He brought on stage Hayden Williams, who was punched in the face on Feb. 19 while recruiting for a conservative organization at UC Berkeley’s Sproul Plaza. The assault was captured on video and almost instantly went viral and became a cause celebre on Fox News.

“If they want our dollars, and we give it to them by the billions, they’ve got to allow people like Hayden and many great young people, and old people, to speak,” Trump said.

His administration has yet to provide any details of when it would produce and how it would enforce such an executive order, but the very concept of a central government arbitrating what is and what isn’t acceptable speech on a college campus is downright chilling. Moreover, the assault on Williams is a decidedly flawed case to argue for federal intervention.

After all, neither Williams nor his assailant were students or staff members at the university. Berkeley Chancellor Carol Christ rightly condemned the attack as “reprehensible” and having “no place here.” The 28-year-old suspect was arrested March 1 on a felony warrant.

Beyond that is a context that hardly suggests the university administration is hostile to conservative views. It has spent $4 million in the last year to ensure the right of conservative students to “safely and successfully” hold events, Christ said. It settled a lawsuit last fall with the nonprofit Young America’s Foundation that effectively locked in UC’s pledge to accommodate conservative events even if protests are threatened.

This is not to dismiss the concerns that institutions of higher education can have a leftward tilt from faculty to campus atmosphere, and that it sometimes can result in hypersensitivity about conservative views regarded as unduly provocative or even hateful. A college or university should be a defender of vigorous dissent from conventional wisdom, right or left. The limits of acceptable discourse should be a point of tension — and discussion — on every campus.

But defining and enforcing those boundaries should not be the purview of Trump’s or any other administration.

Floyd Abrams, one of the nation’s preeminent lawyers on the First Amendment, has testified before Congress about his concerns about restrictions of free speech on campus. Yet in an email exchange with me, he expressed his serious reservations with Trump’s threat.

“The notion that this administration will promulgate and enforce rules leading to stripping research and other federal funding of universities deemed to have provided insufficient protection to free speech principles seems to me ... more than alarming,” he wrote.

Abrams said “I asked myself” if he might feel different with another administration — and concluded that he was even more certain that such powers were too dangerous to allow.

“The First Amendment, after all, is rooted in distrust of government,” he wrote. “I think that distrust is warranted even if a government less hostile to the protection of free expression were in office.”

Conservatives who may relish the notion of Trump’s thought police cracking down on liberal-leaning universities might ask themselves if they would be equally comfortable with giving a future president, say Bernie Sanders or Alexandra Ocasio-Cortez, the authority to cut off funding to Liberty University or other institutions with a rightward bent because of real or perceived bias.

Harmeet Dhillon, a state Republican party official and attorney representing Hayden Williams, said she thought Trump’s executive order was “a great idea,” though she is awaiting details. Her disdain about the treatment of conservatives on campuses dates back to her time at Dartmouth College.

“I think it’s at crisis levels at universities,” Dhillon said. “When I speak to young people, as well as professors, everybody feels like they’re not able to speak freely and be themselves on campus because they have this politically correct dogma that is superimposed. I’m not talking about tolerance. I’m talking about your not being able to say X, Y or Z — or you’re being tasked out of the circle of grace.”

She acknowledged the “response was fairly swift” after the assault on Williams but nevertheless held the university accountable. She said she would “reserve judgment” on whether to file a lawsuit against UC Berkeley, as Trump suggested in his speech.

“They have actually fostered an atmosphere there where people who assault conservatives, people who threaten conservatives, can get away with it,” Dhillon said, adding, “Berkeley is a safe space for violent leftists.”

Erwin Chemerinsky, constitutional scholar and dean of UC Berkeley Law, said Trump was trying to “solve a problem that doesn’t exist.” Despite a few high-profile exceptions, he observed, free speech is “alive and well” on the nation’s campuses.

There is hope in the ultimate check on Trump’s whims: the U.S. Constitution, which has foiled the best-played bluster of the president on matters from Muslim bans to transgender troops to sanctuary cities to census counts.

“I don’t think Trump has this authority,” Chemerinsky said. “Only Congress can put strings on federal money.”

John Diaz is The San Francisco Chronicle’s editorial page editor. Email: jdiaz@sfchronicle.com Twitter: @JohnDiazChron