There's no rhyme or reason with these critters sometimes. I've had those BP feeding blues before and got over it. I was feeding live and only had one snake back then so it was an even bigger pain. My critters are a lot more predictable these days. Even though a few of them will go off feed annually it's always seasonal thing. You can scale those offerings back to every 3-4 weeks if you want. He's well established so he'll eat again eventually. At least you've got your boa to dispose of the refusals.