May 27, 2021 | 8:39pm | Updated May 27, 2021 | 9:04pm

Is there something in the California water that makes Silicon Valley’s censorious dweebs so damned shameless?

On Wednesday, Facebook ­revised its policy of banning posts suggesting the coronavirus was man-made — because the COVID situation is, er, “evolving,” as a spokesman told Politico.

Gee, thanks. The flip-flop comes more than a year after the social-media giant banned a well-reasoned Post opinion column by China scholar Steven Mosher that speculated about a potential lab leak. Will our columnist receive an apology? Of course not. But it’s the American people who should be holding the Menlo Park ­tyrants to account.

Think about it: If you were Xi Jinping, and you wanted to deploy an information-control operation over the origins of COVID-19, you couldn’t have done better than to just let Facebook, working in conjunction with America’s bottom-feeding “fact-checking” industry, do its thing.

The Chi-Coms, after all, were held in odium in the US eye long before the first COVID cases arrived: How much more effective — and devious — to have a gazillion-dollar US tech firm shut down public inquiry into the ­virus’ origins, and that with the help of well-credentialed “experts” and “fact-checkers.”

It’s worth returning to what Mosher wrote to see how shameful Facebook’s censorship was. For starters, note that Mosher didn’t definitively claim that COVID-19 had leaked from a lab. What he argued, rather, is that a lab leak should be plausible to anyone familiar with Chinese ­realities. Among the pieces of ­evidence he marshaled:

• The fact that Xi himself had, in the early days of the crisis, warned about “lab safety” as a national-security priority.

• The fact that, following Xi’s guidance, “the Chinese Ministry of Science and Technology ­released a new directive titled: ‘Instructions on strengthening biosecurity management in ­microbiology labs that handle advanced viruses like the novel coronavirus.’ ”

• Above all, the fact that the Middle Kingdom has only one Level 4 microbiology lab that can “handle deadly coronaviruses” — and that lab just happens to be located at the “epicenter of the epidemic.”

Set aside any other scientific questions about the virus (many remain unresolved): Didn’t it at least merit some thought that the country’s sole coronavirus lab is located at the outbreak’s ground zero?

Even if Mosher were wrong — and a growing number of US ­security officials and top scientists are coming around to his side — didn’t Americans and their policy makers have the right to consider the possibility? The virus’ true origins, after all, would inform any number of concrete decisions, not least whether Beijing and the curiously Beijing-subservient World Health Organization deserved US cooperation.

But no. Facebook and its ­“experts” knew better and moved to suppress a vital column, distorting the US debate when it mattered most.

Oh, about those “experts,” whose testimony was used to justify the ban: At least one of them — Danielle E. Anderson, an assistant professor at Duke-NUS Medical School in Singapore — regularly collaborated with the Wuhan virologists, hardly an unconflicted source.

Another “expert” insisted that no “responsible” government would permit such deadly leaks, and the quaint assumption that China ranks among responsible governments was enough to merit banning Mosher’s column to her mind.

Similarly dubious “expert” claims, amplified by partisan “fact-checking” outfits like Politifact, were used to frame as conspiracy nuts anyone who dared warn of a potential lab leak. (Politifact has now quietly taken down its ­denunciation of Fox News’ Tucker Carlson as a leading conspiracy theorist on this issue.)

This pattern of Big Tech censorship, enabled by unaccountable “fact-checkers,” poses a catastrophic danger to America’s ability to govern herself and respond to crises.

The problem isn’t just that it leaves ordinary Americans in the dark, but that it insulates elites themselves from uncomfortable realities — such as the possibility that their beloved Chinese trading partner might be responsible for a pandemic that cost millions of lives.

Enough is enough. Facebook and the other Big Tech giants are irreformable. Only political action — in the form of removing the special status that allows them to act like publishers without any of a traditional publisher’s liabilities — can save us from this private tyranny.

Sohrab Ahmari is The Post’s op-ed editor and author of the new book “The Unbroken Thread: Discovering the Wisdom of Tradition in an Age of Chaos.”

Twitter: @SohrabAhmari