Given the shape of the hip and foot bones of the Kodiak bear, it has been determined that standing and walking upright is completely natural behavior for these bears.
Conclusion (Thus)
Walking on hind legs is instinctive and not a learned behavior of the Kodiak.
Evidence
Given their hip shape and foot bones, standing and walking upright is completely natural behavior for these bears.
Evaluate
The link here seems to be
Do we accept that move? Is it possible that a learned behavior just happens to conform 'naturally' to certain anatomical traits you have?
Do all Kodiak bears walk? Or is it only the ones you have seen humans traipsing around upright on their legs? There may be counterevidence to the idea that walking on hind legs is instinctive. There may be evidence that walking on hind legs is learned (for exmaple, none of the Kodiak bears in a certain group walked on hind legs until they saw a human doing it).
Goal
This argument doesn't seem to be any of the famous flaws, so we can anticipate that the correct answer will call out its central assumption (if walking upright is a completely natural behavior, then it's an instinctive, not learned, behavior) or it will bring up potential objections that one could use to argue that walking upright is a learned behavior for the Kodiak.