Since he is exalted with AV rep he had to have started before level 70. Maybe he just boosted/level granted to 60 then leveled in AV only. Gear doesn't matter all that much pre 80 and I have read a ton of people say how they only quest to 71 then AV to 80 wearing only 60s gear. Even if he leveled from 51 in AV he could just be buying 80 pvp gear.

As for just sitting afk in a BG, that's a separate question. I have read that before the recent afk changes that when you get the debuff you still get the xp but not the honor.