I think this list seems entirely fair to the 2012 Giants. The players who made it are deserving. The only notable names left off the list are quarterback Eli Manning and fullback Henry Hynoski, and you can't say either omission is really a slight.
The brutal truth is that Manning didn't play up to his own standards in 2012 and that RGIII -- who changed the future of a franchise -- was a better player. In the case of Hynoski, PFF gave the nod to Redskins fullback Darrel Young and I'm not going to argue. It's a case of 'to the victor go the spoils.' The Redskins won the NFC East behind a brutal power running game, and Young was a big part of that.
In terms of PFF grades, Young had a +9.3 in 335 snaps (+6.6 in run blocking). Hynoski was +8.0 in 428 snaps (+7.6 run blocking). You could make the argument that Hynoski was slightly better based solely on the grades, but there isn't much difference and Washington did win the division.
Thoughts, Giants' fans? Incidentally, the full list is free PFF content if you want to peruse it.