True, although I think the circumstances would matter. One might visit an art museum and see a naked statue.
I would suggest that it's not the seeing of a penis, in and of itself. After all, they might see penises on horses or dogs. It's a piece of anatomy, like a foot or a nose, just a dangling piece of flesh. The only part of the anatomy which is truly frightening is the brain, or more specifically, the human mind. That's where all harm and malice comes from, and the mind just uses all the other parts under its control to commit harm against others. Some guys joke about letting "the little head do the thinking for the big head," but the little head can't think.
Yep. As I said, people see genitalia on animals. What if a 7-year-old girl sees the penis of a 7-year-old boy? These things happen. It probably wouldn't be seen as big a deal than if it was an adult male. Sometimes, there are embarrassing moments that might happen where someone accidentally walks in the bathroom while someone else is using it. These are just unfortunate mishaps of life, but it doesn't mean anyone is being truly harmed. Or at least, we can tell the difference between situations and be able to judge the effect.
Traditionally, I suppose it's always been that way. But seeing that we're progressing in the 21st century, maybe it's time they look at this rule. As I understand it, cheerleaders are not allowed to date any of the players, so this would preclude any hanky panky if they were to share the same locker room.
I've heard that some teams may start having male cheerleaders. So, would they use the locker room of the female cheerleaders or the male players? Or would they have their own locker room? And what about trans cheerleaders? That brings us back to the original question.