If it really was Zhou who voluntarily wrote the letter for the employees (of course there is some doubt about this), I don't think it's really Musk who's wrong here, as it's meant to be sent to the other employees, and not to the public.
Anyways, anytime this kind of thing happens it's just depressing, which is why I tend to avoid topics like this (and also TTAC, which seems to love these kind of topics). Hopefully Zhou can move on and the company can move on.