Jen can stand up to E.D. only because she has nothing but "foggy air" floating around in that big fat head of hers. Come on... didn't you see the episode clips where she was admitting that she didn't know what half the words meant that were coming out of her housemates mouths!
She don't know any better, that's the only reason she appears to be standing up to E.D. all the time when he comes on the defense.