In the last double eviction Sov actually overtook Heidi as second fave to be evicted, but the bookies got over-zealous with that.
Look at the eviction polls, Sisqo is far behind the other two in those. I don't think Sisqo was annoying enough to have caught up.
The bookies think Vinnie is lord and master of the house, and are practically telling people that Vinnie will win no matter what they think. So they obviously are going to think that anyone that stands against him will be automatically booted out.

I am hoping they are proven wrong once again.