First of all, I mention this fan being a regular fan, both of them are clearly familiar with each other enough to joke like this with each other. Why are you taking offense on behalf of no one here?
Plus, surely you understand if the man asks his male fan to open his shirt so they can check them out, its feels totally different right?
Its a totally diff thing when its same gendered since we mostly have the same thing. Girls appreciating girls assets and boys appreciating boys assets have a totally diff vibe than when its opposing gender doing it.