Jessica Guynn

USA TODAY

SAN FRANCISCO — Mark Zuckerberg defended Facebook board member Peter Thiel's $1.25 million donation to Donald Trump's presidential campaign in an internal Facebook post to employees of the giant social network.

"We can't create a culture that says it cares about diversity and then excludes almost half the country because they back a political candidate," Zuckerberg wrote. "There are many reasons a person might support Trump that do not involve racism, sexism, xenophobia, or accepting sexual assault."

A screenshot of the memo was posted to Hacker News, a comment board on Y Combinator, on Tuesday and was published by the tech website Boing Boing. Facebook confirmed the authenticity of the Zuckerberg post but declined to comment on it.

Thiel could not be immediately reached for comment.

Thiel, a prominent Silicon Valley venture capitalist who served as a delegate and convention speaker for Trump, is a vocal supporter of the Republican candidate at a time when Silicon Valley is wrestling with a stark lack of diversity in its workforce. At Facebook, nearly seven out of 10 employees around the globe are men and African Americans and Hispanics comprise a tiny fraction of the workforce.

"We care deeply about diversity," Zuckerberg wrote in the post. "That's easy to do when it means standing up for ideas you agree with. It's a lot harder when it means standing up for the rights of people with different viewpoints to say what they care about. That's even more important."

Thiel's Trump donation stirs controversy, ire in tech

Sam Altman, head of Silicon Valley’s most famous start-up incubator, also said he would not cut ties with Thiel.

In a series of tweets Sunday night, Altman expressed his opposition to Trump as "an unacceptable threat to America" and his support for Thiel, who is a part-time partner at Y Combinator. Altman said he would not "start purging people for supporting the wrong political candidate."

As a result, Project Include, a high-profile Silicon Valley diversity initiative, said it was cutting ties with Y Combinator despite work the incubator has done to advance diversity and inclusion.

"While all of us believe in the ideas of free speech and open platforms, we draw a line here. We agree that people shouldn’t be fired for their political views, but this isn’t a disagreement on tax policy, this is advocating hatred and violence," Ellen Pao, co-founder of Project Include, wrote in a Medium post. "Giving more power to someone whose ascension and behavior strike fear into so many people is unacceptable. His attacks on Black, Mexican, Asian, Muslim, and Jewish people, on women, and on others are more than just political speech; fueled by hate and encouraging violence, they make each of us feel unsafe."

Thiel made billions by co-founding PayPal. At this summer's Republican National Convention, Thiel was the lone tech billionaire to take the podium, where he spoke about being conservative and homosexual.

He was in the news earlier this year when he came forward as the main financial backer of Hulk Hogan in the wrestler's lawsuit against Gawker Media, which had posted a video of Hogan having sex. Hogan's successful suit against Gawker —which had earlier outed Thiel as gay — bankrupted the media company.