The idea of a traitor has been floated around since Zou. Since then, Kanjuro, Raizo, Shinobu, Carrot, Denjiro, Toki and Hyori and Ashura Doji have been floated as potential traitors and even that there was no traitor. Zou was 4- 5 years ago. Congrats if you "figured out" Kanjuro was the traitor after 4-5 years to speculate and theorize. Doesn't make it predictable. The hints that Oda laid out will be even more apparent now that we know.