I'm making a mathematical statement, not a moral one. I chose "nationality" as my input because the linked article focused on that, but the statement applies equally to any other input.

As already noted, any classifier better than a coin flip will disfavor some groups. The choice of which groups are acceptable to disfavor is political and somewhat arbitrary here. For example, these authors accept disfavoring people based on poverty ("sum of assets") or romantic relationship status ("single or partnered?"), but don't accept parenthood or nationality.