News of Tesla Chief Executive Elon Musk taking a board seat at Twitter has some Twitter employees panicking over the future of the social media firm’s ability to moderate content, company insiders told Reuters.

Within hours of the surprise disclosure this week that Musk, a self-described “free speech absolutist,” acquired enough shares to become the top Twitter shareholder, political conservatives began flooding social media with calls for the return of Donald Trump. The former US president was banned from Facebook and Twitter after the January 6 Capitol riot over concerns around incitement of violence.

“Now that @ElonMusk is Twitter’s largest shareholder, it’s time to lift the political censorship. Oh… and BRING BACK TRUMP!,” tweeted Republican Congresswoman Lauren Boebert on Monday.

Despite Twitter’s reiteration this week that the board does not make policy decisions, four Twitter employees who spoke with Reuters said they were concerned about Musk’s ability to influence the company’s policies on abusive users and harmful content, Reuters reported from Dallas and  San Francisco.

With Musk on the board, the employees said his views on moderation could weaken years-long efforts to make Twitter a place of healthy discourse, and might allow trolling and mob attacks to flourish.

In the wake of Trump’s ban from Facebook and Twitter, the billionaire tweeted that many people would be unhappy with U.S. tech companies acting “as the de facto arbiter of free speech”.

Musk has not articulated what he wants to do as a new board member but he has telegraphed his intentions with his Twitter activity. A week before Musk disclosed a 9.1 percent stake in Twitter, he polled his 80 million followers on whether the site adhered to the principle of free speech, and the majority voted ‘no.’

The employees, who asked not to be named for fear of retribution, point to Musk’s history of using Twitter to attack critics. In 2018, Musk came under fire for accusing a British diver who had helped rescue children trapped in a cave in Thailand of being a pedophile. Musk won a  lawsuit brought by the diver in 2019.

When asked for comment, a Twitter spokesperson repeated a statement from Tuesday that the board “plays an important advisory and feedback role across the entirety of our service”, but daily operations and decisions are made by Twitter’s management and employees.

“Twitter is committed to impartiality in the development and enforcement of its policies and rules,” the spokesperson said.

Some employees that Reuters spoke to were not so sure about the company’s commitment to this.