"A Hole in the World" question

So, I just rewatched A Hole in the World (because it's one of the best episodes of the show, even though I hate it (I love to hate it?)), and noticed something. Or maybe I didn't, because I was too emotionally distracted.

The well goes all of the way through the world, and they need to teleport the sarcophagus to the well in order to drive Illyria out. But they can't teleport her into the well without putting 'tens of thousands' in the path of death. Why can't they teleport the sarcophagus to the part of the well in the middle of the earth where there are no humans in the path?

Well, maybe the question is moot. I'm watching 'Shell' now, and they seem to be saying they got there too late...