Could Navigation Arch Component create a false positive memory leak?
That's how Fragments on the back stack work (and Navigation just uses the existing Fragment APIs): the Fragment's view is destroyed, but the Fragment itself is not destroyed - they are kept in the CREATED state until you hit the back button and return to the Fragment (after which onCreateView() will be called again and you'll move back up to RESUMED).
As per the Fragments: Past, Present, and Future talk, one of the future changes coming to Fragments is an opt in option to destroy Fragments on the back stack, rather than having two separate lifecycles. This isn't available as of yet.
You have to null out your references to the views in onDestroyView as that's the sign that the view is no longer being used by the Fragment system and it can be safely garbage collected if it wasn't for your continued reference to the View.