The man said FDR was the biggest scumbag to ever hold office for his internment of Japanese American. In that context its entirely reasonable to point out some Presidents were Slavers. I know some of you snowflakes would prefer not to remember that some American Presidents, maybe even some you're fond of, were indeed piece of shit slavers. But that's the reality.
No, it's not. We can have a discussion about other shit, without you bringing up slavery.