It turns out i solved the problem by renaming my Staff template from archive-staff.php to page-staff.php (or anything else for that matter), thus specifically telling WordPress not to trust the template hierarchy logic and to consider that url as a “page” url, not a custom post type archive.
If you happen to have a use for this function, be aware that it will mainly work for page templates. Anything else needs to be tested, and post archives will not work.