i don't know if it's true, it's just a fantastic scenario in my mind--but chloe used to be harkor's girlfriend. then they broke up. later gallo publicly said that harkor was a piece of shit human being (likely true).
http://www.vincentgallo.com/writing/kingcrimson.html
then years later harkor's ex sucks gallo's dick on film. it just connected the dots ha ha-- completely arbitrary (i'm not paranoid but my imagination is).
i don't know. according to ebert the scene works and "is not gratuitous"
http://www.rogerebert.com/reviews/the-brown-bunny-2004
but maybe a "revenge suck" ha ha