You're writing things that Kaido never admitted
If Kaido was afraid of Oden, he wouldn't let him have his swords in the cell
Oden could have freed himself easily . Especially since his wife was visiting too.
Kaido isn't the one risking anything
He simply didn't want another riot, kill Oden and get with it so that wano citizens become depressed
Oden had two chances and didn't beat Kaido
He didn't do it the castle for hours 1v1
The only reason Oden even landed that move was because kaido was in dragon form taking Oden lightly.