He won't be getting possessed himself just because his mutation makes his entire concept of a body/mind/spirit really confusing...

He doesn't really have any significant energy output (besides exploding himself), so he'll be pretty useless against the spectres. I'd be all for him to help any possessed friends through "cognitive recalibration", though!

Otherwise, he'll probably just focus on minimizing damage and helping with repairs and putting out fires. He'll probably collect whatever debris he can find, but would rather pass it along to someone who might know what to do with it rather than just keeping it for himself.