Did anyone ever see Mel's movie "Conspiracy Theory?". Mel is into conspiracies, it was handed down to him from his father. I can see how he might like F911 in a way. I am sure alot of this was just Mel being gracious, and appreciative of how another independent film maker has bucked the odds and succeded.
'Conspiracy Theory' actually directed by frequent Mel Gibson collaborator Richard Donner (Lethal Weapon movies, Maverick).