He has a high bounty but he isn't a miracle worker. He was focusing on both the deal with Sanji and the vision he was having of the Luffy clones coming out of the cake. In that moment he didn't know where his focus should go, just like the other children had no idea what to do when Sanji wasn't shot. Man was just straight up confused. I doubt it has anything to do with Sanji's Haki ability. Though I really need to see a fight between him and Sanji.
Also, is Sanji and Pudding being a package now back on the table in a big way? If they end up actually married this will have gone completely not the way I expected.