I dont see the need to gamble here. MP1 might be a loose player but someone has already gone allin. You know for value alone no matter what MP1 is going to make the allin call. Its free information i think. Let the hand play out get another free read on MP1. Stay out of the hand and enjoy the show. No need to give away your chips. If he does it again later and you have a strong hand play him than.