I couldn't find any language about that, maybe I missed it. I did find the language pasted below which I interpret to mean that you can't choose a location at the point of assignment of the upgraded cabin. But I don't see anything about changes to location after the upgrade is processed.
Can I choose the location or specific features of the upgraded stateroom?
No, stateroom location and amenities will depend on availability. We can’t guarantee a specific stateroom location within the upgraded category.