As a couple of readers commented, they've walked in on peers - both straight and gay - stroking away. Sometimes they laugh about it, but acknowledge it's such a common practice no one has any reason to hide.
Sometimes, they say they actually join in.
The Dad from the Common Ground posts had this to say:
"Good lord, after having told my sons there's no reason to be ashamed, if they walked in on me jerking off I wouldn't hide. How could I? It would be a bit contradictory, wouldn't it?"
Good point. And that made me wonder if the guy who walked in on his father had ever been caught strokin' the stick by his dad. Maybe that's the problem - his father chastised him for masturbating, and now he's been found to be doing the same.
That would be plenty reason for him to be feeling very guilty and not wanting to talk about it. Whatever the issue is, I hope they get it straightened out. Life is too short to have to worry about things which should be accepted fact.