(1) If the manager did PIP purely as a way to prevent team transfer, then yes I agree that it is clear bad behavior that should be punished. But I am not sure if that is the case. Say this guy was the lowest performer in the manager's team and was on track to being PIPed anyway. Should the manager now be forced to PIP someone else just because this guy is moving to another team?

(2) There are way too many PIP horror stories from Amazon. It is evident that managers even hire people just to PIP them later. In that kind of environment, such bad behavior is encouraged and normalized. Then this particular manager might not be significantly worse than any other person put in a similar position. If the culture is to blame, then scapegoating one manager will just deflect the blame.