Re: Problems in a dojo
I usually find the expression "Who do you think you are to ..."
is an indication that the person has nothing upstairs.
But it won't help to point that out.
It sounds like this brown belt is a petty tyrant who has an inflated view of his abilities. You are bound to encounter a few. They get especially hysterical around testing time. I wouldn't judge a person by his antics before or immediately after a test or exhibition. Just breath and stay alert.
The advise to politely decline to train with him seems reasonable, and perhaps this is a good way to bring attention to his attitude, and he will himself realize he had better straighten up. But if there is no improvement and the kancho does not intervene, then this is one of those times when I would agree that you may be better off finding a new dojo.