But once a recruiter has this type of experience with a few older candidates, they will be more likely to discount older candidates in the future, regardless of whether those later individuals were willing to do 60+ hour weeks or not.
There's no magic button you can push in your brain that says 'don't form conditional expectations based on protected categories'. If you're a recruiter and older candidates keep blowing you off, would you really continue to put in the same amount of effort to try to recruit them, even if you consciously attempted to?