Why is he doing it?
As he explains to WoW Insider, t's partly to try out the philosophy of pacifism in a decidedly violent virtual world, and partly to see if he can do it. From the interview:
As they say, "Read The whole thing".
Show us your kung fu: what's the actual nuts-and-bolts reality of this character?
Both my priest and my rogue try not to hit anything, although there's always a chance of a misclick when trying to open a quest item with mobs fighting near it. Both of them always wield a fishing rod, so any accidental hits won't increase their weapon skills. Neither of them will do quests where they have to kill things. In battlegrounds, my rogue will throw bombs to interrupt flag captures and stun people and may even accidentally kill players low in health or nearby critters. My priest only heals, so he is actually closer in roleplaying terms. Neither will "get around" these limits by grouping and having other players do their dirty work. In terms of bragging rights, I intend to keep my rogue's weapon skills (dagger, thrown and unarmed) at all 1s. My priest will also have all 1s, but it won't be obvious on WoW Armory that he has no offensive spells beyond the level 1 Smite all priests start with.