Bit like using the Hitler-bomb, a sure sign of a lost case. You just pulled a circular argument, if you didn't notice, "Blacking up is racist because blacking up is racist". Doesn't address the point that it isn't, because you then pull a secondary logical fallacy in the syllogism that because all black people dislike blackface minstrels, and blackface minstrels are musicians, then all black people dislike (insert any other category of musician here, including border morris, molly dancers and soul singers). It's in the same class of false logic as saying Gordon Brown knows nothing about economics, and Gordon Brown is a politician, therefore no politician should be entrusted with the economic management of the country. Possible, but stretching a point too far.
I once had a boss who used to be a specialist in that technique, abstracting a case so far up into the realms of the esoteric it no longer had any relationship with reality, before redefining it down in terms which suited him. He soon lost all respect.