Makes you wonder whether Kizaru experienced young Whitebeards strength in person to make such a statement. Iirc, Kizaru was shown following Sengoku in Shiki's chapter while Aokiji followed Garp and Akainu most likely Zephyr.
Would help my opinion that Sengoku was WB's main fight from the Marines. They seemed to have a closer interaction at MF then Garp and WB.