My belief is not that the individual person will affect the horse’s ability to maintain what he has learned, rather it is the quality of the conversation offered by anyone handling the horse, that either supports or “undoes” any training learned here. Obviously if you were violent towards him he’d remember, but more so, in his case, he just wants to know that someone knows what is going on, and will support him.
So to address your concern for him “losing” his evolvement/re-education with me, it will maintain and will last the more you are able to offer the same type of conversation as I’ve been doing. So my goal in your visiting him is to watch how I interact with him and to see/believe the “conversation” he offers through his body language, emotions, behaviors, etc. to better understand how to interpret and recognize the initial, minor behaviors of when he shows concern, defensiveness, etc. and realizing how early you need to “be there” to help him through something, rather than waiting until he commits to a negative or fearful thought, and only reacting after the fact. The goal is the more confidence he regains here with me, the more he’ll be able to “handle” even if with a human who isn’t as aware as I am. But on the flip side, even if he looked “quiet” in the riding videos of him, many, many things have been missed. His jumpy-ness with flyspray, the water hose, stuff touching his sides, that isn’t something that just appears. I’d guess as I opened the door for him to offer his real feelings about the human experience thus far, he has a lot to purge, in order to feel better about being with people.
Today I worked loose with him in the round pen asking him to come over and present himself to have the saddle blanket put on (from both sides), the girth lie across his back, and eventually the saddle. All the while he was loose, so any time he was bothered by the pressure of the gear, he was allowed to leave, sort out his defensiveness, and then he chose to come back over and stand mentally and emotionally quiet, while I put stuff on him again. We got to where he was eventually totally relaxed. He blew and blew and blew his nose. He was the most focused, with the most amount of try I’ve seen thus far.
A lot of this rehabilitation comes from observations too. Like when I experimented with turning out his two pasture mates and leaving him in a round pen loose, on his own, while I went off and did other things. He didn’t scream, he didn’t look dramatic, but he pooped three times in 15 minutes, and was gently “busy” moving the whole time until I returned. While I was still doing other stuff he kept gumming the air like baby horses do, yawning, chewing, sighing, scratching, all signs of being bothered. But because it didn’t look dramatic, most people would have not “seen” it as him being bothered. The good news was, me showing up, made him feel better.