I think August as Piniocchio theory is buoyed by his actions. (But of course, until this last ep I was convinced he was Bae.)
He referred to Rumples as "Papa," but is that really lying? He was just using another name for Rumple (in a sense).
As an earlier poster pointed out, if he is Pinocchio, his statements to the Blue Fairy in Storybrooke would still hold up. We know that Gepetto is in town. He was seen working as a janitor in the jail, and I could swear that he also had another scene with Archie in Storybrooke in Archie's flasback ep. Therefore, Booth could be in town to see his father.
There was a donkey sitting on his desk next to the typewriter.
Plus, in his convo with Gold he was stating facts. He then let Rumple mentally fill in the blanks and see what Gold wanted to see.
So, if Booth is Pinn, that means that two of the fairtytale characters know who they really are - Pinnocchio and the Mad Hatter/Jefferson.
Emma seems to trust Booth. He may be the kick in the pants she needs to begin to believe. If she does then begin to believe, even just a little, would that be enough to save Pinn?
From what we saw with Jefferson, if Emma allows herself to believe, even if for a second, magical things can happen in Maine.