A friend's story

my friend is a very talented person. He led one product into market and facilitated another one. They also have several early stage projects going on. His group used to be very big. At the point of getting into administrative track for his career developement, he received some comments "not good people management skills" from his boss. My friend kinda accepted the reality and just tried to achieve more as a scholar. Then his boss lost in a political power fight and left. My friend then was shuffled into another group which is headed by a much junior person and the next level boss is the one who won the power fight in the organization, i.e. an enemy. My friend then got worse reviews, many of his people were put into other groups and now he received an official performance improvement warning. He is actively seeking otehr jobs. But this is a tough environment. It takes more time to get one, especially a senior position. Is there anything he can do to make things better so that he can stick around until getting the next job? How can he deal with a hostile next-level manager (site head)?