It's a good thing your forgiveness isn't required. I trust God to make that call.
Luk 23:34 Then said Jesus, "Father, forgive them; for they know not what they do."
If God can forgive those who tortured and crucified his son, I pray that He will forgive Mel for his boorish behavior and hurtful words.
You are correct that ultimate forgiveness does not come from any of us. Nevertheless, we still should in no way be so quick to give our own forgiveness to antisemitism.
We don't know for sure if the guy is an antisemite, but it's starting to look an awful lot as if he is. I've always had the feeling that Mel was a good guy, and maybe he is. I still don't like this glimpse of his dark side.
We hear alot on this forum about people who are attacking Christianity. How about a little forgiveness for them too? Because you can bet that some of them have good intentions too.