It really depends whether he plays a game that warns about it. The dashboard only warns about a Moderate NAT if you run a network test. Of the games I played, only Halo 3 warned about Moderate NAT. Halo 4 doesn't bother anymore.

So I don't think he's not "very informed." He's the normal player base. I don't even bother setting up NAT anymore and it works fine, even though I know I should go through the rigmarole of doing it.