How did he determine your horse was proud cut? Did he take blood samples, because unless there is an actual testicle to feel, he would not be able to say without blood tests that the horse is proud cut. I still stand by the fact that its a behavior issue. No matter whether he's intact, totally gelded, proud cut, there is no excuse for him acting like a ninny. I work with stallions, all the ones I currently work are VERY well behaved, listen no matter whats going on, and ignore the mares in heat until given the go ahead to get excited, and even then they pay attention to the handler and what the handler is asking. And only in the breeding shed to they use a stud chain on their stallions. He really just needs someone with the time and patience to work with him, and teach him manners. You probably won't be able to "sell" him, not even sure if you would be able to get a "rehoming fee", but at the least I'm sure that you could find a decent home if you decide to give him away. Best of luck to you.