The main culprit in that missed call, as it usually is, is that the guy was out of position. You can't see a tag play that happens (or, in this case, doesn't happen), through a man's body.
He should have asked for help, I would bet the first base umpire saw it. We've all seen the replay and if he says he definitively saw a tag, he's a fucking liar, because it wasn't even close.
Fire the lot of them.