In the last couple of weeks I have been working on some round pen training, Clinton Anderson style and T is really doing very well with it. Someone has definitely worked with him in this or a similar style before and he is very responsive to the cues. I asked the BO's son to watch me work T in the round pen today as I explained what I was doing. I told the him to carry the stick I use and drive T away when he comes into his field to feed and keep moving him off until he is ready to let him come in and eat. Hopefully that will help, T is a big boy and I don't want him to hurt anyone.
His manners are great with everyone else and he is fine for the vet and farrier who are both men, so in my case I'm chalking it up to "something" about the BO's son that my horse just plain doesn't like.