Think about it for a moment. He has remained unimpeded throughout this entire process, and it is implied that he may have done this more than once.

I don't doubt that this world could have incompetent officers. [People who aren't as spirited as Judy.] But don't you think someone would have tried to stop him by now? Or that we may have seen someone else.

If something has happened to cause the population to decline rapidly, perhaps there is no one in this world left to sacrifice. And that is where we come in.