I don't think anyone will change your mind on this subject.
You trust people an awful lot just because of some 8hr class? I hear what your saying, but I've met a lot of dumb CPL holders too.. As long as someone isn't pointing at me or acting out.. I usually don't bat an eye.. I have been around a few people open carrying that I did not know and were not police officers. Usually if you are open carrying, you know a little bit about guns/gun laws.. or else you would probably not be aware that it is legal to do so. Id have to say the guys conduct wasn't the best, he could have answered the questions a little less douchey.