Its very hard to say i think, i mean this guy spams so much i dont think there is anything we can do.
I would say in the least we should expose him as being just a spammer.
I doubt tough serious sexists/racist would bother coming here. Atleast not in such degree that it would be an annoyance.
My personal stance is when convenient making a funny insulting reply, because i dont think its a good idea to just stop posting alltogether and ending up like /comp/ or whatever.