I don't get this. Yes, he had no shot against Sarah or Tony, but that's not a reason to offer yourself up as a sacrifice, it's a reason to flip. No matter what Natalie said on her return from EoE, I can't believe someone with an ego the size of Ben's wouldn't think he had a chance against Natalie or Michele, especially if he had voting out Sarah and breaking up the power couple on his resume.
And had he done that and then beaten Tony at fire at F3, I think he potentially could have won. Which I would have HATED, but what he did instead was baffling to me.