Twitter employees previously enjoyed an unfettered culture and aren't used to an ambitious and disciplined leader. Working hard for 40 hours a week from the office is the norm, so it shouldn't be a surprise that the company's owner is calling for just that.
Musk isn't just cutting costs to save money or ridding the company of poor performers; he's eradicating dissent. Multiple employees have been fired on a whim for simply liking a post critical of the CEO. If Musk wants to build a successful platform, he should refrain from declaring war on the people who design it.