Judging from those pictures blake i would assume that he's a member of "his cousins" worldguard, so even if this was a malicious act no action would be taken on our part as he's a member of the worldguard.

Also, if they are family, i would assume it's more of a joking act than an act of malicious intent, so just performed for a laugh.

Will look into it in game if it's rasied as a problem by the owner of the house, the solution will most likely just be to remove phantom from the worldguard however.

I cannot stress enough that people should only add people to their worldguards if they can 100% trust them, as the moment you add them to your worldguard they are free to do as they wish.