Here's a clip of Bill O'Reilly being deliberately thick about the Saltsman song parody thing. What O'Reilly and, frankly, both of his panelists don't get is that in addition to the racially stereotypical "Step 'n Fetch It" voice, the offensive and racist aspect of the song parody has to do with who is peddling it...
...A Republican white man name Paul Shanklin. And it was made famous by a racist white Republican man named Rush Limbaugh. And now it's being circulated by a Republican operative named Chip Saltsman who doesn't seem to understand why people are offended by it.
The Republicans have, to say the least, a problem with race (see my book for lots of examples). So it stands to reason that when white Republicans dive into an attempted comedy piece that features an offensive voice and lyrics that contain the words "magic negro," there's a very strong possibility that it comes from a place of conscious or subconscious racism.
Yes, The Simpsons or The Daily Show might be able to get away with this kind of bit because in those contexts, the hypothetical comedy would very likely skew into the realms of satirizing or mocking people like Limbaugh who deal in racial stereotypes. Coming from Republicans like Saltsman and Limbaugh, on the other hand, it's just wrong.