Their blades bare no semblance to Odens, not their Haki.
He was saying they are not as good as Oden, so he was questioning why people like them are able to cut him. When Luffy damaged Kaido, he saw his potential to become stronger, when the Scabbards damaged Kaido, he viewed it as a fluke, because they are nowhere near Oden's level nor do they have the potential to reach it.