Like Garp let scape Luffy, Ace etc.. There are Marines who are friends with some pirates and cops who are friends with thiefs.Because Roger had a "title" doesn't mean that Roger was the strongest in all the One Piece world, he was "aknowledged" by everyone with the title of the "Pirate King" not the King of the World or The Strongest being in the World. If you don't understand i don't care -i'm bored that everytime i say something you have to reply-. Your intelligence looks like your avatar's face.
Sure, it doesn't mean he was (but it does imply he was), but also doesn't prove the contrary.
You're the one being stupid here, insulting others because you don't have a good argument to reply with. Might as well move on.