You said that to the Professor directly?
You talk of attitude, however I personally believe that attitude comes into play when an Instructor thinks that parents do not have a right to question his teaching methods. In your earlier statement you said that some parents would make a good corner ref as they have seen a round house long enough to know if it scores. If that is the case and I see an Instructor that I know is not teaching the proper technique should I say nothing?
First of all, my comment was to the point you made that you are the customer with the checkbook. I gave you my response to that. What you are talking about above is a different situation.
I think it has to do with approach. I would say that the parent of an underage student has the same rights as the student to politely ask the instructor questions. If you approached me with the attitude that you are a customer with the checkbook, and demanded not only answers to questions but also demanded that the teacher teach a certain way, well, then you already know my response to that. If you politely and respectfully asked me about something (like you did above), then I would give you a corresponding polite and respectful answer.
In the days of the pioneers, students were not allowed to ask questions; but today, questions are not only allowed, but actually encouraged, as long as it is done in the proper fashion. What the proper fashion is I would think would depend on the circumstances and the individuals involved.
Of course, we are talking about a private dojang, which, rightly or wrongly is the kingdom of the head instructor. We are not talking about a public organization such as USAT, which is supposed to be open to everyone. In that case, I do believe that members can and should be able to ask questions and to a certain degree demand answers, especially if the organization has a stated policy of transparency, like USAT does.