He regularly argues things like that blacks have too low an IQ to be taught things like correct handling of weapons, he posits the existence of honey traps, where activist women try to seduce him and other leading Open Source figures, in order to accuse them of sex crimes. It goes on and on.

"Roughness" or being a "misfit" is not how I would characterize the problem.

I'm sure he knows how to admin his own mailing list with other people like him. But I wouldn't expect any mainstream project or club to tolerate garbage like that indefinitely.