From my experience (which is less than 20 years let me say!) I understand that there are MANY, MANY
options available to both parties during a technique. What makes it aikido is the ethical choice not not to take all of the shots that you can. (Congratulations on being the person who practiced aikido in that pair.) I guess that I may have in my frustration beaten him to the hip-check, or some other atemi, after the 3rd demonstration. After all, if he can get you you could get him equally well.
Certainly, I've enough skill to perceive when a person's input ...is genuinely useful and when it is not. I can tell now when I'm dealing with a stylistic difference rather than a legitimate mechanical/martial concern. And I can see when ego is motivating someone to "correct" my technique rather than a sincere interest in seeing me improve as an aikdoka.
It sounds like you've decided that you met up with some stylistic ego differences. I think I agree from the description.
Let this person go. Its not worth your energy.
Enjoy your next seminar