If he wanted a backrub, then it is irrelevant whether or not the hairy 40 year old men were into boys as young as him.

I don't know about you, but a backrub from somebody you're kind of attracted to can be quite different from someone you're not. Just like kissing such a person on the lips even briefly is different from doing that with your sister (assuming you're not attracted to your sister in that way, lol).