I am hesitating to call it a bug, because one could argue that it is an accepted oddity to simplify the code (and thereby save resources).
Personally, I wouldn’t create an issue because it will detract focus from other and more important tasks - e.g. developers reading, understanding and prioritizing this issue instead of fixing/reviewing other more critical issues/improvements.
The decision is however fully up to you, just make sure that you add one or more use cases where fixing this will add significant value to rclone.