A better question would be, why would you do an online survey of only black men, if your goal is understand "the unique challenges of brain health and cognitive decline faced by Black men"? Surely you would want to leave it open to at least white and hispanic men too, to at least try and see if those challenges are in fact 'unique' and have some sort of baseline or comparison? And it was an online survey of self-reported measures recruited by an existing survey service (CloudResearch), so they were not limited to an existing sample of only black men - they went out of their way to restrict the sample.

4 legs good, 2 legs bad.