At least Mel was drunk.
Not an excuse...but, Richards was just whacked. I think he was trying to be funny...but he failed miserably. He was just out of control angry.
I have seen people say and do really dumb things when they were drunk. The out of control, near breakdown stuff that happened on the stage the other night was simply scary.
It seems to me that lots of today's comedians use racism, sexual humor, dirty words, etc, to get the shock type of laugh. Videotaping them at comedy clubs to prove they are racist or anything else is silly - unless we're actually going to start disaproving of how vulgar comedians in general have become.