So... Dumbledore did know all along, just like cannon, and sent the map to the twins for plausible deniability. He can get away with that because he doesn't mind when people think him a fool.

That's mixes well with the idea that the Goblet of Fire kills Voldemort if he takes the stone. It's simply a well set up trap and because Voldemort thinks he's smarter than the rest he walks into it.