Originally Posted by
Yobaba**:
“I don't see the purpose of not evicting Frank. I would rather Jodi, Jojo or Kara return than having Frank stay.
Though I suppose if they were doing a returning HG vote then Frank would have won that anyway.”
Frank's one of this season's stunt castings due to his famous dad, the other one which I can consider was Willie due to him being Russell's brother. Grodner obviously thought that it would harm the show to see her two stunt castings go before the jury phase has even started, so saved Frank through this twist.
The other theory could be that by keeping Frank in the game and in the process reviving the Shane vs Frank feud it would keep the targets off the back of the coaches, and allow them to make it further in the game while Shane and Frank go after one another.