Of course not, this is a gross oversimplification. I was just surprised at how well the numbers worked. I would argue though, that it is a good rule of thumb, i.e. their revenue is not sustainable given the number of employees that they have.

IBM like any company will employ support staff, admin/HR, cleaners, managers and so on. Plenty of those people earn over $100k and plenty of people earn a lot less. Ultimately we don't know the mean salary of the people they're (maybe) laying off.

But hey, it's a Fermi problem, order of magnitude. I would guess it's not too far off.