It was stated before that cage agression is "crap", it's not; and it has nothing to do with feeder scent either, it's agression period, it can & does happen. Hook training is a good idea, for when they are in this state.
In all fairness to the boas, I'm speaking from my own experience with boas, they are puppy dog tame once out of their enclosure.
My male rtb gets such bad agression at times that I have to put a towel over his enclosure, to stop him from striking at any movement.