GreyLord
Legend
This is a jerk move.
Is he the GM in a game you are playing in? Then he gets to decide what system he's running. As a player, you get to decide if you want to play in his game or not. Now, could all the players get together and say "listen, we are tired of 4e, please switch to 5e, or else"? Sure! But it is *his* decision as a GM.
If he's the player, then the GM decides what the system is, and he decides if he plays or not.
Look at it this way: Would you do this to a *friend*? To an adult you respect? No. Then why treat your son this way?
This could have been a great moment - a big gift of gaming books to your son - but instead you made it weird and jerk-ish.

I figure that he just needs a little nudge along. He still has his books, but he really needed to catch up with the group. I can't drop him as his dad so obviously I keep playing...but even with my like of 4e...that was a bit much. He still has his books if he wants to go back to them in the future...but for now...I'm trying to get him to get into the game the rest of us have been playing...either that or play AD&D as I'd prefer that recently to playing 4e. (AD&D at least is easier for me to handle multiple characters and can be built for you handling henchmen).
Love him...but got sick of the game. At least he looked at the 5e books this evening. He can't say he can't afford the books anymore (I got him all of them...so that's definitely NO an excuse), though he still likes the 4e art. He DID ask me to order Volo so that's a good sign.
If he takes this and runs with it, maybe he'll bring back the rest of the guys (and girl) to game with him on Saturdays like we used to.