PLAY! It's that simple, if you don't play than I'm not going to stop someone from coming in a taking over your group. I get that RT can be a problem, but if you cry RT the moment someone challenges you...you have two weeks to get it sorted out or you lose by default. (If an agreement between the two players in question can't be made) I don't want to have to put my boot down, don't make me.
Don't mess with your caps to prevent people from challenging you. It is up to you to set your caps, and if you don't allow strong alphas/strong master vampires on submission. That's fine, but that being said for the PLAYER who is submitting that character. If you brought in the character for the purpose of challenging put a note on the CS. Staff might step in and approve if the character meets all other requirement (fleshed out history etc). Remember...you're position is not safe.