I see that I am answering this 20 months after posted, so my answer is definitely not timely, but hopefully I can make it substantive.
I wouldn't worry. I just wouldn't. Most preppers engage the process not out of anxiety, but rather out of a host of more benign reasons. Some just want to be tacticool, and this (gender bias aside) falls into the category of "boys will be boys". Some, have experienced loss and scarcity and so having stuff around is insurance, plain and simple. Some simply value individuality and self-reliance, and don't trust their opposites, collectivism and the welfare state. Some simply want to protect, starting with the smallest circle and working out to the largest they see themselves capable of exerting some amount of control: self, family, friends, neighborhood, etc....
The point is, if your preteen is seeking to extend his control over his environment, pulling him back from that and asking him to "trust" that the world (or your situation at home) will just be alright, is leaving him over the abyss. It will soon become evident that he has other responsibilities with his time and money and an exclusive focus on prep will naturally become obvious as detrimental.
You say that your son has been into politics and world history since he was very young. One thing that a study of history will expose you to over and over is instances in which savages, tyrants, secret police, plague, economic depression, natural disasters, and a plenitude of other things rolled over individuals, some of whom made it and some of whom didn't. The fact that your son feels that he can become one of the ones left standing, with those he loves around him, speaks volumes of good about his character. It also speaks volumes about the fact that his concerns are all directed outward and that he must therefore consider the things at his back (family, home, school) safe.
And if you and he are capable of having a conversation, don't, for the love of Pete, send him to a counselor. Last thing he needs is a label he doesn't choose for himself or isn't given by someone who loves and respects him.