IMO there's way too much concern about ONE person who clearly doesn't care about your concern anyway, and not nearly enough concern for all the junior students who are being harmed here and who have to put up with him all the time. Getting senior students to babysit him is a partial solution in the short term, but those senior students' time could be far better spent helping people who want to learn.
That. The guy's sucking all your time and energy, and other students are getting shortchanged.
It's really no different than technique. If someone doesn't know how to do something, or know that they're supposed to do something, you teach them. As they try to learn what you're teaching, you help them and give them feedback. If they refuse the lesson, you don't keep trying to teach it -- and you definitely don't shortchange your other students to try and get a point across when it's being rejected with such evident determination.