Using "white" as a casual negative adjective is weak. I can respect non-whites using it as a term of anger or hatred. We're all big boys. But seeing it used as a term of self-hatred leaves me feeling more than a little disgusted.
Well, I wouldn't necessarily call it self-hatred, just as it's reasonable for many males to "hate" the male gender. I have serious issues with the social construct of gender, with its inculcation of aggression/subordination and bizarre attitudes, dress codes, etc. As a male, it's acceptable for me to "hate" maleness, and I think that's better than leaving only females to dismantle patriarchy.
(Then again, in the sense that I dislike the odd parts of me which have been bent by race and gender, and actively wish them to disappear, maybe there is something to calling it "self-hate". But it's like the self-hate of a novice, who wishes to transcend their current inability.)
So hopefully we might accept that race is a similar, complicated -ism, and it's fine to be a "race traitor" or gender traitor if yours dominates.