Re: how many back talk would you take?
It's also possible that his criticisms of how you're doing it are valid, too. E.g., maybe you're making some mistakes in your movement or timing so it actually doesn't 100% 'work' (e.g. maybe he really can hit you), which makes him doubt that it CAN work that way. That would be entirely normal if you're not super advanced, as you're also in the process of learning. If that's a possibility it might be better to let the teacher or more advanced students do the correction and teaching, even if what you're doing is closer to what the teacher is teaching than what he is doing....
Also some people just have to take time and experience for themselves what works and doesn't work and why things are taught a certain way before they become convinced enough to want to try to learn to copy it... if at least the teacher and most advanced students are doing things solidly, then I guess in time he'll see for himself if it's something he wants to learn to do... or if he decides he doesn't want to learn to do what they do, then presumably eventually he'll leave.