Sometimes foolish consistency is the hobgoblin of little minds.
Other times consistency just keeps people from thinking that the forum software is confusing. (The commenter, not the reader.)
I’m glad I finally figured out how this most basic aspect of the software works after using it for years so I won’t be confused any longer.
I suspect that a simple solution that doesn’t compromise your position is actually possible. Just display the response icon for the user that just left the comment, and just on that page-view.
Confusing inconsistent behavior gone. No need to clutter up the UI with needless information. And I agree that having it there is bad. That’s why I don’t want to change the setting, but do want to find a way to fix the UX for the commenter.