Well, I rewatched on YouTube the dancers I voted for (Ellie, Annabel and Bobby) and although I was very moved by Bobby's dance, I realise now that this was mainly due to the backstory plus the lyrics of his music. His actual dancing (and also the choreography) did not seem to be that wonderful on a 2nd viewing.
However, because of the backstory and Shirley's tearful response, even if he is in the dance off tonight, I suspect it would be hard to vote him off.