If Kuzan was above Kizaru
He'd be introduced after kizaru and be matched up with people stronger than that Kizaru fought
Kizaru : Kuzan opponents :
Luffy > old Garp
Old Ray =< Old Garp
Marco >~ Jozu
Injured Sentomaru > injured Cracker
Garp Is called the strongest old man in usopp gallery when Whitebeard was alive.
Idk where you got Garp >= Rayleigh from, Garp >> Rayleigh especially when Garp still trains and Rayleigh didn't touch a sword since decades.
悪ガキ2人と最強じじい!
Two bad kids and the strongest old man!
Notes: On DeepL, the "strongest" alternative word is "most powerful" so its not in reference to pure physical strength, and even if it was, it would need to reference haki too, making his haki the strongest.
Also, this is from the Usopp Gallery of Volume 50, during Thriller Bark, meaning it would include Oldbeard.