Of course "racist" is a pejorative, unless you're just identifying a fellow racist or something. If you're asking in terms of "can it be used as an insult", sure it can. Any defining term can, you $#@!.
See what I did there? I think you're a self-admitted $#@!, so was I insulting you or just defining you?
"$#@!" is an insult for the most part, but hey - @Alyosha is a self-admitted $#@! so then again maybe it isn't.