It sure would be awesome, but it seems impossible.
First, there's no way all the specs could be the same as the Rab jacket (weight, features, fill power, and almost price) but be box wall construction instead of sewn-through.
Second, as far as I understand, it would be ludicrous to create so many tiny / narrow baffles in a jacket with box wall construction. The sewing job would be insane. If you look at box-constructed jackets that are clearly labeled, such as on Montbell or Montane's sites, you can see that all of them have rather large baffles and the seams aren't so tightly beveled. In other words, just visually, the Featherlite doesn't appear to possibly be a box-wall jacket.
But yeah, if it was, that would be awesome. If that was correct, I feel like we would have heard about this by now, though. I believe the mistake is just on Campsaver's own site.