They are willing to do somewhat goofy things in the name of charity (and come cultural awareness). Of the persons pictures, Jim Hines is the only one I haven’t been regularly following for at least a few years (and he was the mastermind behind this).
Specifically, this bit of… well… you decide what to call it.
For those that are just looking at the picture, there is a point behind it (the hyper-sexualization of cover art for some genres).
The fact that they don’t take themselves so seriously that they can poke this kind of fun. And do it for a good cause.