Lots of people are starting to get very sick of Frank. They want Tiffany around, since she's the one with the most obvious vendetta against Frank & Bridgette-- particularly in light of her exit speech on Thursday night. So they voted Bronte out instead.
And I'm not a Bronte fan, but I will say that she showed a lot of class.
I have to laugh at the whole "I was Natalie or me, there were no other choices" line of thought. There were plenty of choices. Frank has shown he is wiling to put up someone from the 8 pack; he's stated that the alliance has served its purpose. That said, there were plenty other members of the 8 pack who aren't quite so close to Bridgette that he could have put up, had he chosen to do so.
When will Bridgette come to understand that the cutesy, giggling, skipping, hero worshipping, "Frank knows best" thing is NOT going to win this game for her??