There is a difference being a stupid person, and doing/saying/acting stupid Marc, you know that. Actually you know what, satire is probably the wrong word now I think about it (I'm quite ill today, excuse my temporary mental health). But I do think that to think this is a racist sketch is stupid.
Poor comedian, telling stereotypical unfunny racist gags, audience doesn't like it (because they are not racist), comedian dies, everone rejoices at the death of a dirty great bigot.
The sketch obviously contains racist content, it's undeniable, but the sketch as a whole and the message or intention are clearly anti-racism.
The more I read over the original sketch the more I think it would work better picking on more groups. One racism, one homophobic, one sexist. That way you can't be misconstrued as attacking any particular groups.