I'd doubt it. Racial slurs aren't his style at all. At most he would do a mocking deconstruction of why you can't say it.

Maybe I'm old, but I don't take salacious anecdotal reports on forums to be be worth considering, whether or not they're plausible. You might not believe this, but people on the Internet used to just make things up -- and the good ones would even try to make their apocrypha believable!

Here is the racist rant if you are implying the accusation is 'made up' . https://www.youtube.com/watch?v=vXp6ArvXcT8

Yes, we all know his persona and ongoing public drama. It's obnoxious. But I'm not sure why that would make a random story in some forum worth taking seriously.

From the video, he is advocating for an ethno-state based off a single poll regarding the feelings people have about the phrase 'all-lives matter' answered by only 112 black people. I wouldn't say this is just 'part of a persona'.