Hi PFB, I wasn't there but that trainer sounds rude, interfering and insecure, not to mention in need of a few lessons herself, in manners and probably also in some aspects of horsemanship. She may be great at coaching jumpers, but that doesn't make her an expert at all other disciplines, such as dressage, gaited horses, etc, nor does it mean she's automatically better than non-trainers at such things. Not every person who'd good with horses and riding ends up teaching others for money.
I agree that touchy horses like the "bolter" need to be taught to tolerate normal leg contact, and that the aim is to ride it like a normal horse, not a ticking bomb.
I also think that the instructor is being rather forward in getting involved with your horse, and needs to back off. You've every right to coach people you allow on your horse - it's your horse, you know your horse best, and you don't sound like you're at all uninformed about riding.
Look, I've no idea if this is a fair comparison, but many moons ago when I learnt to ride in Europe, one of our agistment centres had a jumping teacher who yelled all the time and made the horses in the arena nervous with his presence. Much as I would have liked jumping lessons, I was put off by this. I also noticed that he was "rushing" horses and riders without what in my view was the necessary groundwork, so lots of horses kind of charged around the jumping course without communicating with riders properly (and then the instructor yelled even louder). The dressage instructor was totally the opposite: Preparation, lots of exercises - calm, calm, calm.
Ah, the politics of riding establishments...
Good luck with your riding and your horse, you sound like you're on the right track, don't let anyone spoil your enjoyment, or discourage you from thinking for yourself.