Yup, the very last boss of Hellfire Ramparts seems to be an open invitation to ninja-ing that loot. Just like the Cache of the Firelord (another notorious ninja location), a chest spawns after the boss dies, and anyone in the group can step on over, open it up, and grab everything in it. Pookybear (nice name) has noticed this too, and Blue answers: It probably won't happen.
It's kind of a weak answer, but then again, when I think about it, I haven't had it happen to me yet. But all of the Ramparts runs I've done have been guild runs (where we all know each other), and I'd imagine most of the runs on all the servers are people leveling up together who know each other-- as we see more PUGs come through, this might be an issue. Have you guys seen a ninja after Nazan? It's hard to believe it will never happen, but the community has been doing pretty well at casting ninjas out of guilds and such. The first time I saw that chest, ninja is the first thing I thought of, but maybe Blizzard just doesn't see it as a problem. Has anyone seen a ninja in Ramparts? Why doesn't Blizzard just turn the loot into, well, loot?