Revealing his theory to us this afternoon, David explained how he felt that favourites [tag]Ruth Brown[/tag] and [tag]Jaz Ellington[/tag] could get overlooked.
Just eight acts remain in the competition, with four more leaving this weekend in the semi-finals.
David told us he felt Bo was "unique enough" to win the viewers vote with her songs.
"I think the public might start to think that Jaz and Ruth are possibly safe and start to vote for someone else," David suggested.
He added: "That's a scary thing, where you're so popular that people think you're going to be fine."
Bo is currently the third favourite to win the competition after a brilliant performance at the weekend.
Will.i.am described the 27-year-old's cover of Rihanna's Love The Way You Live as "a million times better" than the original.
This Saturday will see Bo and the seven other acts battle it out for a spot in the grand final.