Lolwut? Do you have any idea how many people, on a day-to-day basis, send dick pics to sexual partners? I'm not saying it's necessarily wise, but it's absurdly common. As a gay man who uses Grindr, I've literally run into 2 guys who haven't been completely comfortable sending pictures of their cocks. It was dumb including his face, for sure, but still.
There's no reason to fire someone. It won't be long before the people WITHOUT dick pics somewhere are the minority.