Some guys do have big egos. I'll say this, and it's just my impression from reading the original post. It sounds like you actually do have little respect for him and his school. Based upon your description of his school and his classes, my impression is that you kind of look down your nose at him and his instruction. As a result, I wouldn't be surprised if the lack of respect you feel manifests in some way in your interaction. In other words, it sounds like you were VERY respectful based upon your description, but I wonder what your tone and body language were saying, while you were being so polite.
I guess ultimately what I'm getting at is that there are always two sides to a story, and while you were certainly not wrong to decline the offer of a "free" seminar, I'd be inclined to give the guy the benefit of the doubt until I met him myself.
I see your point Steve, but I'm going to respectfully (no pun intended ) have to disagree. IMO, I dont think that anyone should be bullied into allowing someone to give a seminar, free or not. Perhaps the OP couldve said, "Yeah, sure, give me your contact info and I'll get back to you at a later time" that later time never happening. But the instructor in question could've been a PITA and after not hearing from the OP, taken it upon himself to repeat the lines of BS that he initially gave.