Shouldn't the blindside be the blindside, no matter what the situation? This wasn't in the "hitting zone," and the player came from horizontal-to-behind the player he hit. If that were a hit in the neutral zone, it would be a 5 and a game, but since it was just above the goal line, it's a legal check.
It doesn't make sense.
EDIT: This may be a product of my scientific obsession with symmetry...
No. If you drive your car into a tree while looking the other way you can't claim the tree was "in your blindside". Blindside is relative to the expected direction of play. Rule 48 was put in place to eliminate the backchecking headshot on unsuspecting players, not plays of this type.
If all headshots are to be eliminated, that's a different debate, but the league has made it clear that that's not the case.