On the one hand I can well believe that Twitter was massively overstaffed, and the staff that were there were pampered. The fact he's fired 1/2 of them and another bunch have resigned (voluntarily, or under duress) and it's still operational tends to suggest that. I saw it said elsewhere that Twitter has grown massively in headcount in recent years, despite not having grown itself as a business. There was - in my humble opinion - a lot of fat that could be trimmed.
There is also an argument to be made that Musk has never been coy about his approach to business, attitude to WFH, etc. There is evidence of layoffs at SpaceX, return to work mandates imposed on Tesla staff, etc. People working at Twitter had to haved expected this sort of treatment when he took over.
On the flip side I can't see how his managerial style will pay dividends in the case of a company like Twitter. I don't think he can upend the expected work culture, perks expectations and work/life balance in those class of companies, in Silicon Valley, though I don't doubt a certain breed of managers and company owners will be watching how well he does to see if they can recalibrate their own balance of power.
The s**t hot developers and other professionals will have plenty of options available to them if they haven't left already. What he's likely to end up with are people who can't resign - for whatever reason, e.g. H1B visas, dependant family, financial commitments, etc - and career sociopaths. It's debatable whether those people will be the cream of the crop.
I fortunately barely care about Twitter, so all of these goings on is more fascinating than it is troubling. I think it would be fair to say that Musk's star has diminished greatly from how this has all played out, though, and given he has massive debts to service each year due to the purchase price he has a very limited amount of time to do something the company has never achieved before - monetising casual users.