V.M.
at that age, its just fun to chase the ball up and down the field. I think making sure he knows what to do, like what the positions are, and when to run and when to stay and how not to touch with your hands might help. our experience hasnt' been that the volunteer coaches don't do much of it.
maybe have him spend a little one on one ish time with the coach, so he/she doesn't seem scary? reinforce that he can't mess up.
I am like you in my approach to things. I would hate to force him, but i also think it would be so good for him and so fun, that i'm not sure i would allow him to completely back out of it. i love that you stayed to watch the game.