This is something which has been on my mind for a while and perhaps it is worth discussing. Oda is known to throw hints here and there in the story foreshadowing future events. In this particular he threw us a very obvious bone.
In here we see kinemon having a pretty extreme reaction to law's words about kaido and joker working together. The point of this thread is to discuss why exactly kinemon and mononosuke would be so shocked about this.
Another detail which should be relevant to this is the fact that kinemon, mononosuke and a couple other samurai had as a destination dressrosa.
Now, how are all of this connected? If 3 samurai, who by all intents and purposes would seem to be strong, mobilized to dressrosa I am of the idea that they would be there on a mission. Kinemon seems loyal to wano so whatever they were doing would obviously be related to wano.
Now, if their reaction was like that it would seem they, and perhaps wano, has some sort of conflict or relation to kaido. Perhaps joker was selling stuff to kaido and wano at the same time? What are your thoughts?
Now, first of all, i would like to quote Kaiten because it think it is a good theory
destination was Zou, they only landed on Dressrosa because they met with disaster, whatever that may be (i think it is the weather i described above). I agree though that they were probably on a mission. The word "Zou" has several meanings, besides "statue, image or portrait" it can also mean "elephant". I would not be surprised if Zou is a South Asian themed country (India, Thai, Cambodia). Furthermore, i think it is possible that the Samurai, including Kinemon, were sent to Zou by the Shogun in order to make allies against Kaidou which is in turn the mission.
I will keep with the theory that there is feuds fighting over power and they went to Zou to find allies and Kaidou is helping the opposite feudal lord.