There are all sorts of ways this could happen. But honestly I don't see the point in playing guessing games when we have pretty much no useful information from the people on the scene yet. I will say that I can think of no reason why a setup *should* have been in place that could cause this. But that's all the more reason to reserve judgement until some usable facts are on the table.
And to Chip, I'm not sure I see this as inevitable. I've climbed there perhaps a dozen times, and never had any difficulty protecting the anchor or the climbing rope. Often, when belaying from the top, there isn't even anything but my ass that's going over the edge. It goes like this: Anchor pieces -> my harness. Climber -> my harness. My body is sitting atop the cliff, looking down on climber. Nothing but soft tissue over the edge.