I had thought so as well, however at a gun auction I was at not too long ago one went on the block as non-restricted. The cfo passed the paperwork through right away. After that auction I looked into it, and the Squires Bingham is not on the "variant" list. The Armscor 1600 and the AP-15 also are not restricted (if you can find one). The AP-15 is the only one of the group that actually looks like an Armalite. How the AP-15 slipped through, I have no idea. ...As anal and backwards the CFC is.
The Squires Bingham M16 I can see not being restricted because if you look at it, it's just a Model 20D with different sights and AR'esque stock.
.. "BUT", since it's one of those guns that everyone assumes is restricted, you'd do well to treat it as such when you transport it and use it in public. We all know how well an "no it's not, yes it is" argument can go with a cop.
BTW.. the one I saw at the auction went for just over $900 because everyone there assumed that it was restricted as well and they we're sneaking under the radar. Turns out that misinformation made it probably the most valuable SB M16 around.