How can we definitely say that though? We don't even know what staff has left, nor what the plans are to replace them if they were critical.

This is exactly the point I was going to make.

I have no doubt Twitter and most companies could be run in maintenance mode with 20% of the current staff. However figuring out which 20% is the tricky part.

Typically I only need 20% of the lights in my house to do what I need, but that doesn't mean it's a good idea for Elon Musk to come into my house and just randomly remove 80% of my lightbulbs.

To successfully pull off such a major change in staffing in such a short window would require knowing the ins and outs of the company extremely well.