What kid, at your son's age, is going to sit down and read instructions? I don't know of many. Listen, your s is at that age where the games are the big thing. I know I was concerned about my nephew being "hooked" on the gaming at that age, but he outgrew it. Instead of television, it's the gaming. Your h doesn't understand this gaming stuff because he didn't grow up doing it, in fact, he's probably too old to remember that the television was the thing and yes, Atari, were the thing back in the 60's, 70's and 80's. I don't see where it's a huge worry at this point that he needs to make an issue of it.
As the parent, he should have sat down w/your son and gone over the directions w/him. Sorry your h's feelings are hut, but I wouldn't send the gift back because that's like punishing your s for not doing what your h expected him to do.
Again, I would just text back and say "H, I'm sorry things aren't working out the way that you had hoped, but again, this is something that should be discussed in the counseling session". Cut him off w/his complaints.
I swear, he sounds like mommy dearest. He best be careful how he handles this new parenting style or your s may not want to go there and then your h will have some real issues to deal with.
No, you aren't the cause of this issue. It's funny he really didn't start up big time on this until mommy dearest got her britches in a twist. Your s is young and I certainly don't want to see him have bogged down w/chores that aren't necessary. I wouldn't pay your h no mind, but be prepared w/your list when you go to the counseling session.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.