Precisely. IBM paid them to take their fabs away (yes, they paid them, not the opposite, they were so obsolete that it was basically a waste disposal operation)
was there some regulation preventing them from just shutting the plants down and selling off the real estate and equipment? severance payments too high?
IIRC they had an agreement that Globalfoundries were to take the fabs and further develop them to shrink to better nodes. I think it was less than a "take this crap off of us" and more of a "we still need fabs, so here's some money and please continue running them for a while". GloFo then utterly failed at competing with TSMC, Samsung and Intel which was quite a problem for IBM. In general if you have a certain design you can't immediately port it to a different fab, you need to engineer it around the constraints of the fab node and process