Not that it's anyone's business, but showers were used as a ruse to sexually abuse me as a child. Maybe my experience is just extremely rare and unique, but I doubt that.
Him being gay isn't what makes it wrong or weird; him being an adult makes it wrong and weird. I'm not accusing him of anything, and I'm not saying every adult who showers with a/their child is a predator, I just know firsthand what could happen.