It's County Parks & Recreation, so I could complain to them, but I'd like to think the coach will correct the bad technique and do his job and teach the proper technique. He comes across as a stand-up guy, but...
Time will tell! I don't want to be that kind of parent and interfere, but this is illegal play in practice from his own teammate. In a game it would be a penalty and in the NFL it'd be a personal foul and maybe even unsportsmanlike conduct on the helmet tackle, which nowadays could result in a fine and possibly a suspension.