Very highly unlikely in my opinion. Birds are a predator of bps in the wild, not to mention that a macaw would have little or no trouble killing a bp, and from what I've seen of the behavior of my cockatoo, they will defend themselves most vigorously. No I didn't intentionally put them together, but my bird becomes visibly agitated if I bring a snake into the room. And as was already said, a good secure cage is the best defense in this situation.