It's true you can buy 'replacement' mag bodies for your already legally possessed pre-ban high-capacity magazines. However, the magazine bodies in question are stamped as LEO mags, which means they can't be used as replacements. Possession of these mag bodies and even one follower, spring and baseplate means Steve's buddy would be screwed, as he now has the means to assemble a post-'94 hicap mag that he has no legal right to possess. So your right, vic, just possession of a stripped LEO mag body wouldn't get you a trip to the big house. But you'd better not have any other mag parts, so what's the point of having them?
As far as possessing a stripped LEO receiver, same deal. However, you can't make a post-ban rifle out of it if it was ever an assembled LEO rifle. If it came from the factory with the LEO markings and was never assembled into an 'assault rifle', you can do what you want with it. By why would you want to deal with the hassle?
So legally, he can strip the mags, throw away all the AR15 magazine innards he owns and keep the LEO mag bodies. Maybe he can use them for paperweights. He could sell the bodies to an FFL dealer, who could probably re-assemble them and sell them to an LEO. Technically, he could sell the bodies to anyone as long as he didn't sell the other parts of the mag. In reality, do you want to be the one the purchaser says he got the LEO mags from if he gets busted?
So Vic, you're only half right. The mag body is not restricted in the sense that possession of it by itself isn't a felony, but if you have the LEO body and the parts to make a complete mag (and don't think ATF wouldn't stretch this to mean parts from legal pre-bans you already own, if they really wanted to), you're screwed. Sounds like a restriction to me.