Honestly it’s kind of hard to know how to respond to this.
We recognize that “I was just joking” isn’t a universal defense, otherwise people wouldn’t have had an issue with minstrel shows. But as a society we’ve come to recognize that humor can be persuasive and can inform people’s beliefs about what others are like. It’s similar to how sites like 4chan that started out with cultures that were drenched in ironic racism eventually were just actually racist.