I think the Mutnats are just in the Blue area, the Grey area was created by the Inhumans and Noh-Varr. But if the Mutants try to kick them off screw it war, the only reason the Mutants "won" the last conflict was because of inside knowledge of New Attilian, and a number of Inhumans helping them in the end. But now with them just kicking the Inhumans out of a place they literaly built up from the ground up the Mutants wouldn't really get that help and no Beast giving them secret info.