But Kaido and King's fire will be different than regular fire and Kinemon can't cut them. They were the fire who caused the forest to burn for 5 days despite the heavy raining in Oden flashback.
Why then? Shouldn't we get a specific reason for how this works then?
Like there is no real reason for how kin'mon cuts fire right? He cut the pink hazard fire with little to no effort so we don't know if it was easy or hard or what he needed or if it was conditional. He just did it. What you are proposing is that there should be very rigid parameters from the get go.
We should've know how kin'emon does this, then we should know how much energy he needs to do this. And then we should know the specific difference between a chemical explosion and kaido's fire that specifically makes it too much or too different from what kin'emon can handle.
See this will never happen in One piece unfortunately. It even goes all the way back to Luffy vs Enel and how Luffy just being rubber should not have actually mattered in terms of the actual physics surrounding lightning and insulators.
There are no such specifics in on one piece unfortunately. It makes as much sense as "Magma burns fire" so it's as concrete as Oda says it is. Kin'emon can cut fire and that's the end of that. Like how Ryou can cut Kaido and that's the end of that. There will never be any specifics to any of this