No.
He didn't say you were racist.
Did he?
Quote his claim of racism.
For starters, how about Old Sarge using the term "sheethead" in his post? I don't have a dog in this fight, my ancestors fought on both sides of that war. But it doesn't take a genius to know that calling a man "sheethead" is equivalent to calling him a Klansman.
My grandfather was accused of being a "niggerlover" by the Klan in the rural 1920's south, and he was forced to physically defend himself from 2 carloads of halfwitted troglodytes with his 12 gauge Winchester to avoid being horsewhipped.
I assure you that I would take it as a personal and very offensive insult if I were called a sheethead on the basis of an innocuous post such as the one that started that exchange.