Or maybe people just have bills to pay and/or want to support their families. A little critical thinking and empathy goes a long way...

When you first lose everything, in the process you end up having to pawn expensive principles like that, so when other things like this happen, it's easy to seize the opportunity.

Were you ever homeless and starving?

Doesn't seem bad to me. Come back for a pay bump and get paid while you search for a new job.

How about if they doubled your previous salary?

I wouldn't go back, regardless of salary offer, unless I didn't have any other jobs lined up. If I'm not employed than any job (even a bad one) beats being unemployed. But if I was employed, I wouldn't go back to a job where they laid me off for stupid reasons, no matter how much money they offered.

I guess the crux of the issue is that there's no guarantee that the company would not find a different, equally harebrained, reason to lay GP off.

There's no guarantee in any job that you won't be laid off.

True, but if you already know that a given company tends to fire on a whim, you'd be excused to feel a little bit distrustful.

For how long?

As a homeless person, do not wish homelessness on yourself.

I doubt it :)