I have a 3-year-old green gelding that I'm working with. He's a big 17hh draft cross. He's very quiet and relaxed with pretty much everything. However, for some reason he gets really antsy in cross-ties, especially if I try to tack him up and cinch him while he's tied (even if I only do it loose). He starts to raise his head up and back up, and because he's so big with tons of strength, I've been afraid of putting him in cross-ties in case he breaks them and hurts himself somehow. He's usually okay if I only groom him in them and don't leave him tied for extensive periods, but I have just started doing him in his stall instead. I've been doing a lot of natural horsemanship ground training with him and I've read a lot about how a horse should be trained to stand still for everything even without cross-ties, and that cross-ties are actually quite dangerous.
Since trying these exercises with just a lead and rope halter, he has begun to stand quietly to get tacked up and groomed either in his stall or in the arena or wherever, and I can easily do him in his stall even without a lead rope (although I use one for safety anyways in case I need extra control). He's much more content to have that freedom and he's fine if I have just a lead on him - it's just the cross-ties that seem to unnerve him. I don't understand why, because like I said, he is pretty much bombproof with everything else.
Is it a problem if I continue with this method since he seems much more pleasant and relaxed with it, or should I force him to learn how to be tied with cross-ties?