Well he's no longer our problem, he's someone else's, hopefully.
I'm curious as to why he is even bothering to learn at your dojo if he believes everything your dojo is doing is wrong, other than to stroke his own ego. I mean it seems kind of silly to be training in something you don't believe in, right? Unless your point is actually not to train and just point out the flaws in others.
I don't believe you can change personality disorders. Behaviors certainly, habits, maybe, but the fundamental basics that makes the guy tick? I doubt it. If his incentives and motivations are wrong, there is nothing on this planet that will stop him from doing what he wants. You can shuffle him to another dojo, but he'll probably do the same thing too.
I cringed when I read about how he acted at the seminar. Yikes. The guy's overstayed his welcome.
I've thought a lot about this in the past. He's been with us since around December, and so far we must be allowing something that is serving him. People only do what works for them. I think he has no plans to get better at Aikido, or to learn our style, or to learn Aikido period. But I do think we for quite some time were allowing him to fulfill a need to teach others. Leading and instructing others in my opinion probably serves him in some way, and we've been allowing him to get away with instructing 7th and 6th kyu under our noses. Now it has exploded into a problem. I really can only say we got ourselves to blame, we should of nipped this at the bud. But he's been away since the last class last week where I took better control of the class. He was visibly aggravated with how I was leading the class. I was leading the class directly to control whom everyone practiced with, I did a lot of line ukemi drills... basically he was dis-empowered to continue the behavior he has been up to. If he comes back to my class he'll see the same. My opinion at this point is if you come to my class you are expected to train... and train in the exercises put forth. Not discuss, not debate, not instruct...train!
I hope he gets inspired to train in Aikido rather than quit. Not sure if that's realistic however.