It was a play out of the liberal handbook - when you're losing an argument, accuse the other side of racism.
I won't stand for it nor will I be cowed by it, no matter who plays that card.
No.
He didn't say you were racist.
Did he?
Quote his claim of racism.
"How does an objective statement about whether or not you own slaves questioning your stand on racism"?
Your claim of objective statement can fit here as well.
;-)