First, I've met him too and he was mostly fine.
That really has nothing to do with what he is now claiming. And, to let it go would be to say it's okay for him to claim he co-created Iron Man. It's not okay. Yes, most Marvel fans will know he didn't co-create Iron Man but it's those who might not be familiar that will be mislead. And, over time a lie eventually can become the truth in some eyes if heard enough. As comic fans who have respect for the real creators of these great characters, we should just let random artist make false claims? This isn't a claim of some small time character. This is IRON MAN. One of the top charachters of the MCU and I have too much passion and respect for Stan Lee, Jack Kirby and Larry Leiber for this overinflated ego to pass off that he had anything to do with the creation of Iron Man.
Just my opinion.