We live in a society that still, to some degree, teaches us to respect and defer to our elders. That can add complications to a superior/report situation that

We live in a society that still, to some degree, teaches us to respect and defer to our elders. That can add complications to a superior/report situation that many do not want to handle or which makes them uncomfortable. But while they will feel uneasy about the hire, they may not realize this is the cause of it, and they could likely chalk it up to a general 'bad gut feeling' or such, not realizing their reasoning is discriminatory.