life, liberty and the pursuit of geekiness

I originally thought that we were meant to think that she turned evil in the first place because of the revelation about the Big Crunch, but on reflection I think your interpretation is right. And you're also right that her (moral) logic has holes you could drive a Dalek invasion fleet through. Of course, the same applies to Rusty's plots.

And I'll stop spamming now, I promise.