OpenAI CEO Sam Altman says Elon Musk did “huge damage” to the culture of the AI startup. During testimony as part of Musk’s lawsuit against OpenAI, Altman said Musk required OpenAI president Greg Brockman and former chief scientist Ilya Sutskever to rank researchers by their accomplishments and “take a chainsaw through a bunch.”

Altman conceded that this was the management style the Tesla CEO was known for, but that it was incompatible with his startup. “I don’t think Mr. Musk understood how to run a good research lab,” Altman testified when his lawyer, William Savitt, asked about the impact of Musk’s departure from OpenAI on morale. “For a research lab where people need, sort of, psychological safety and long periods of time to pursue an idea, this idea that you constantly have to show your results, and if they’re not good enough on a short period, you’re going to get fired. That really didn’t work for the kind of research we went on to successfully do.”

Altman added that Musk’s departure “was a morale boost in some ways,” as staff members realized they didn’t have to “work this way anymore.” Musk’s lawsuit claims OpenAI abandoned its original mission of benefitting humanity and that Altman and Brockman tricked him into providing funding for the startup.