One way to read your story is that upper management applied heavy downward pressure, to the extent that relatively trivial changes in the organization were discussed as 'costly' - in an effort to get engineers like the senior staff engineer in your example to pull heroic feats of engineering in a few weeks all by himself, instead of using a small group of engineers / resources.
I think your argument is that 'it worked for him' because he is still there while the managers are not, but reality may be the managers were there to have that effect in the first place and the 50/50 turnover was because they were in the thick of it.
I think your argument is that 'it worked for him' because he is still there while the managers are not, but reality may be the managers were there to have that effect in the first place and the 50/50 turnover was because they were in the thick of it.
That'd be my cynical take, anyway.