Yep. You're right. Her reasoning's aren't explained very well.

It was just contrivance. There is no logical way to have Ivy make a decision like that, which is why I'm guessing it was glazed over. It's also probably why Rachel didn't try to convince Ivy, because there would have been no way to have Ivy continue to refuse when it was pointed out how nonsensical her position was.

Pierce-pissed all over it!

LOL.