Considering that AK normal is right at the beginning of the relic quest, I'll just point out that gear does not necessarily equate to experience—they could easily have bought the gear with another class and actually be a fresh 50. When I hit 50 on Paladin I was doing small pulls in AK normal, because it was my first level 50 dungeon and although I had great gear from my Warrior I was a bit of a mess—I legitimately forgot where I put Circle of Scorn, for instance, and didn't remember what it looked like, and wasn't used to the cooldown timing on it yet.

It's possible that a well-geared tank who isn't pulling much simply isn't very confident in his skills (or his new level 50 moves) yet, especially in AK normal.

Just food for thought.