It sounds to me (from what I can understand anyway) that the agression is all a result of poor husbandry. Sounds to me like maybe the BP has no heat source and is in a too small tank and possibly no hide??? I think, and I'll admit I only have limited experience with BPs, just the two that I have, that if she were to get into a proper enclosure with proper heat and humidity, and was made to feel safe and secure, she would probably calm down and do well. My only concern would be any health issues that the BP may have acquired through improper husbandry. When and if you decide to take on this BP, their may be vet bills to consider as well. Especially if she has been without proper heat and humidity for a length of time.

Another thing, try to tell the person that has this snake that if she is having money issues, then now is DEFINITELY not the time to be looking into getting a bearded. I can't believe that the person is trying to rehome the BP and admits to having money issues and yet is considering getting a bearded, which probably require a bit more money invested into them than BPs do.