I think the most important point that almost all airsoft beginners, especially those that haven't done research and only have heard about what it is is that airsoft is not a loophole in the law whereby anybody can go purchase an ultra-realistic gun and shoot it around in public because the purchaser knows it is not a real gun. No. Obviously nobody else knows that its not real. And the repercussions of doing said activity is far greater than anything you'll achieve by shooting it around. Inside the house? Okay, as long as you aren't seen. Outside is a 100% no-no, unless you own a large private wooded property, by which you should notify the authorities and take precautions to let the public know.
In any case, I understand your son's interest, it was the same with me, I thought it would be really really cool to own a restricted firearm replica and show it off, but luckily proper research and some common (or not so) sense prevents teenagers from doing anything unfortunately.
What's more important: morality or the freewill? In our society most people would say freewill. But we mustn't forget our morality.
Our morality guides our freewill to do the right thing.