He saw the people who hurt him in Luffy and that includes Oden.
Just like Luffy, Zoro damaged Kaido (with Enma, the sword that is literally Kaido's PTSD no less) but, according to the spoilers, Kaido takes no note of that or draws a connection to Oden and Zoro. Oda made it a point for Kaido to see these legendary characters in Luffy and not the other Supernova. Again, THIS IS NOT AN L FOR ZORO.