[wsbizwsa]

It's actually not uncommon to be more loose with the formalities during the usual class and then get more strict about it when you have notice that a high level sensei is coming to visit. I've seen rokudans and godans do it so I wouldn't blame your instructor for doing the same thing. If you use strong words like "fake" then yeah, you were out of line. You should make allowance for the fact that this person is not a sensei and has no sensei to rely on for teaching related advice. OTOH, the instructor is out of line to tell you not to come back over such a small thing. Kendo is for everyone, and imo, we shouldn't exclude people from kendo just because we had an argument with them or for some other philosophical or political disagreements. If I were you, even if I didn't plan on going back to his dojo, I'd at least apologize and move on.