Oops, posted early...

... From Lee and said his own quote based on it. His quote didn't have racist intentions, not to mention the fact that a quote from a racist person isn't racist just by it's association.

Finally, the blackface part, which is the most serious in my opinion. While that is true, a song didn't have to be racist to be performed in blackface. While performing songs blackface is (I think) widely agreed to be racist, any song could be sung in a similar fashion, and often non-racist or topical songs were simply sung in that style.