The point isnt to stand in a corner and trap the enemy and rack up kills. The point is to capture the flags and hold them long enough to gain victory. He played cowardly, he hid in a corner with an overpowered weapon and weaseled out a MOAB.
You can try to justify it all you want but the fact is THAT is a cowardice and nooby way to play the game. Camping with overpowered weapons and not going for objectives.
If he had REAL skill he would have capped A and when the enemy spawned at C he would have made his way over there and capped that, and back and forth, all while keeping an eye on B while traversing the map. If he was doing that then I would have taken note of his paths and strategies and I would have respected that MOAB, but the way he did it was just plain noob. This guy is at the bottom of the barrel when it comes to CoD players.