If it is, then they were harmed by being exposed to a pervert.
If you think a grown man showering and 'horsing around' with them isn't, then according to your definition of 'being harmed' they weren't.
So, again, is he a pervert or not?
How does this harm work to the ill of the boy? Yes I am being devil’s advocate, for a reason. You’re shooting from the hip and I’m exposing it. I think you will fall back to an argument of overall risk of bad morality, if not injury. But I say, show where this actually occurred to the boy, even one boy.