Why are you so convinced about Kuma's consciousness being inside the robot? I didn't come across such theory before. I briefly threw out myself in the dark as a possibility, but still you seem very convinced of it.
- Why would Kuma rampage Marie Geoise like the ancient robot 200 years ago?
- Why would the ancient robot from 200 years ago, who had no connection with Nika (800 years ago), react to the drums of liberation?
Anything you may come up with will be far-fetched and completely random. The robot has no reason to react to Nika, Kuma has no reason to rampage Marie Geoise, it's just random and we haven't gotten anything in the story that would suggest why this would be happening.
The easiest and most logical answer is that their consciousness were swapped. Oda loves plot twists (look at the traitors in Wano).
- Kuma (inside the ancient robot) reacted to the drums of liberation because he knows about Nika from the Buccaneers and he has been waiting for him for his whole life.
- The ancient robot (inside Kuma) is rampaging Marie Geoise like he tried to do 200 years ago, that's what he was programmed for.