To understand how messed up things are now, especially how covid is still a thing, Musk is ordering his employees to work in person or he assumes they left the company.
Musk tweeted following the decision suggested that remote working was a facade. Employees should pretend to work somewhere else. Really? If you're a billionaire, wouldn't you want to ensure the safety of all your employees to make sure you stay a billionaire?
According to the IRS, a full time employee is anyone who works 35 hours or more per week. Contracts would have to be looked over and revised accordingly. Some employees were hired as remote workers when covid first hit, so there's assumption those contracts will have to be re-written.
Will this last? I would assume changes will be made accordingly, depending on what happens. Asking one of the richest people in the world and the owner of twitter to do changes is highly doubtful.