I am of the understanding that "academic success" means "success at school" where "school" usually means a college or university or other formal institution of higher learning. Self-taught people can be many things, and most of them are more important than being an academic success, but the one thing they cannot be is an academic success.
In other words, I think your son has it right.
Whether or not the world SHOULD be this way is a further question (and one fully worthy of debate, and which I would not mind debating with you or anybody else here on the Mudcat). But according to what the phrase actually means in common usage, I'm afraid the world-as-it-is favors your son.
Sorry, sweetie. :-)