Interesting theory! Here’s the thing I keep getting hung up on. Everyone knew III was coming (and sooner than expected). From all of our other theories, he’s going through the life cycle. If that’s the case, then how could he have been BoS? What I mean is, it seems everyone knew about him already and knew he was a little rascal. So I don’t know if he could have been BoS because they would have had to get to him in the “womb” so to speak.
If BoS is controlling III (maybe like the other theories about taking over a body), then who is right and who is wrong now?
Also, if III is going through a life cycle, I can’t wait until he gets to senility and I remind him about the money I lent him 😀