There was another bird that was going to be removed for the same reason a number of years ago - I think in Minnesota somewhere - it was attacking people on the ground at quite a distance from the nestsite. I think in the end the pair moved or she didn't return or something and they never did follow through. I just don't quite remember which means now I'm going to have to hunt up the bird.
It was suggested that we might try to remove Jules because of where she was nesting and because she was so aggressive - the latter compounding the problem caused by the former. I opted to try to get her to move and when we couldn't get that didn't get much pick-up, we moved her chicks when we could without injuring them knowing she would follow. It was a risky move worth trying but it was still a compromise. In the end, we did manage to get a barrier installed so she couldn't nest in her preferred location and that was the year Beatrix took over.
It would be interesting to know exactly how aggressive BB is/was. If she was a risk to people working or living nearby, she could very well have been injured by someone trying to protect themselves - remember there was a workman (in Alberta?) who was using a broom to keep the peregrines away from him. Something like that could have gone very wrong and the peregrine would have been the inevitable loser. And yes, DEC has a duty to protect wildlife, but wildlife will almost always come second to human safety, even if it is just normal, natural behaviour.
This is speculation on my part, but faced with orders to "do something", taking her out of circulation may have been the best compromise they could come up with. Re-releasing her makes me suspect that they weren't thrilled with the idea of removing her either and hoped that in a new location with a new mate she would be a bit mellower - I can't imagine that the captive facility wouldn't have been able to release her without DEC's approval. Too bad it seems not to have worked, but captivity may be better than a more permanent removal ...
And yes, it was a possibility that she could have been less aggressive in her new situation. Just as every bird is an individual, so too is every pair. Joli is aggressive but much less so with Hart than she was with Cowboy. Cowboy was an assassin but fortunately, he was in place where he didn't cause too too many problems (he wasn't problem-free however) and he wasn't interested in random passersby so everyone could live with him. T-Rex was like Cowboy and that never changed, fortunately, he had the pick of the territories so he only beat on the Project when we had to get close to his nests. Princess is a great protector, but she learned how to pick her battles from Trey and she has taught Ivy and Smiley.
just my two cents ...