I'm not sure that in the absence of buybacks that they would have just sat on a pile of cash (I bet some of them have some cash on hand) and paid everyone during the COVID crisis until that cash was gone. That just wouldn't make sense business wise either.
A lack of buybacks wouldn't change anything here. If you're not working these employees, you aren't going to keep paying them for long generally. Buybacks or no buybacks.
If you don't like the incentive to layoff people who aren't working for you, that's a whole other topic IMO.