Admirals can molest mihawk too. Or are you disagreeing? The admirals didn't really fight buggy for them to know that he is a joke. Only one who fought him in any capacity was aokiji who is currently an ex marine. So even if he knows the truth( which I don't think he does) he ain't gonna open his mouth. Vast majority of marine hq belives buggy is strong as fuck. He survived getting iced by aokiji, evaded kizaru's light attacks and got luffy and jinbei out of warzone