Self-described “free speech absolutist” Elon Musk fired a Twitter engineer via a tweet after his former employee disagreed with him about the company’s app performance on Android smartphones.

Elon Musk has already fired approximately half of Twitter’s employees, now he’s begun firing those that publicly disagree with or criticize him on the social media platform. Some have been publicly fired by Musk via Twitter, and others have been informed they’re fired shortly after tweet exchanges with Musk.

On Sunday, Eric Frohnhoefer, who worked on Twitter’s Android app, re-posted one of Musk’s tweets with a comment asserting that Musk’s understanding of a technical aspect of Twitter’s app was incorrect. Musk asked Frohnhoefer to provide more information, then inquired, “Twitter is super slow on Android? What have you done to fix that?”

Frohnhoefer explained in a series of tweets what could be done to fix the app, but Musk didn’t respond to the insights. In response to a user’s query about why he hadn’t given his new boss feedback in private, Frohnhoefe who has been an engineer at Twitter for over eight years responded, “Maybe he should ask questions privately. Perhaps he could use Slack or email.”

Musk announced late Monday that Frohnhoefer had been terminated. Frohnhoefer publicly shared Musk’s message, including a saluting emoji that was popular among employees when they were let go earlier in the month.

Forbes reached out to Frohnhoefer on Monday asking if he had received any formal communications from the company about his firing. “Nope, nothing,” he said. “They’re all a bunch of cowards.”

Frohnhoefer said that he didn’t have strong opinions of Musk prior to his purchase of Twitter, stating that he was in the “wait-and-see camp,” when it came to his opinion of Musk’s management but since then “it’s gone downhill.”

“No one trusts anyone within the company anymore,” he said. “How can you function? Employees don’t trust the new management. Management doesn’t trust the employees. How do you think you’re supposed to get anything done? That’s why there’s production freezes – you can’t merge code, you can’t turn things on without permission from VPs.”

Reporter Casey Newton of the publication Platformer tweeted that employees are now being fired for criticizing or disagreeing with Musk in Twitter’s internal Slack channels. Newton stated that it’s not clear how many employees have been affected but it “seems like it’s more than 10.” Newton later added that employees have told him it appears that approximately 20 people have been fired over Slack posts.

Newton noted that Twitter has always cultivated an internal culture focused on discussion and dissent, with a motto of “communicate fearlessly to build trust,” and that since Musk’s takeover, no internal codes of conduct have changed.

Lucas Nolan is a reporter for Breitbart News covering issues of free speech and online censorship. Follow him on Twitter @LucasNolan