I think it was during the battle between Law and Blackbeard that it was stated with enough Haki you can cancel out the effects of any devil fruit... Surly Kuzan as an admiral knows that... TFTC.
Lamentablemente la calidad de escritura bajó de forma absurda, ya solo es guion por el autor y no ayuda que le halla dado esa horrible fruta para sacarse power ups del * o meter guionasos