He asked you because you were the only person to call him a racist.
You have yet to supply an reason. Idioms are not a reason to call someone a racist.
It's a little bit like my Hymen idiom (or was that a simile?) - it's late and I drove from Chester to Home at 55 to see what MPG I can get from a fully loaded 3 tonne van. Pleasantly surprised but rather fatigued.
He is a Hymen because he is a bit of a ...... well you can Himagine