On average, it may be true to say that certain minority groups may be more violent or less intelligent. That doesn't mean it's ok to treat them as such.

It may seem like a glib comparison, and I hope it's substantive enough that it doesn't start a flamewar. But if one person can come to see ageism as equally valid as racism, then they can teach others, who will teach others, and eventually it will no longer be a problem.