Whoops, except that the quest itself hasn't even been invented by Blizzard yet. They haven't said that it requires rep, or gear, or running instances, or really anything at all. We know absolutely nothing about it, and yet this guy feels the need to complain that it's already too hard.
Hopefully, he's just joking (if not, maybe he's just misinformed). But just as I've asked for patience on the PTRs, it's important to realize that everything we heard about this weekend is a long, long way off. In fact, I almost wonder why Blizzard released it so early-- if they've got Zul'Aman, voice chat and guild banks, another raid instance (probably the Sunwell), and maybe even another 5 man coming out before the expansion, why are they trying to get us all excited about Wrath of the Lich King? It's OK to be excited about the new expansion (I am), but it's not OK to pass final judgement on something that hasn't even been created yet. Let Blizzard do their thing, and then when we know details about the quest and what it actually entails-- then it'll be completely fine to complain that it's too hard for casuals.