Obviously extremely scripted, even down to the "I don't like jokes like that." Reads like something out of a bad episode of The Daily Show where Jon Stewart is "clueless white guy" and accidentally says offensive things while Wyatt Cenac winces or something like that.
It's not funny, but it's not racist either. The point of the joke was "Is Bill de Blasio a racist? NO just kidding, politicians and black people have completely different meanings for that word."
This kind of uncomfortable humor is only useful when it is used to challenge our prejudices or make us take a hard look at ourselves and laugh cathartically a la Dave Chappelle.
This would be way funnier if De Blasio had like a history of saying unintentionally racist things and he was lampooning himself. This was totally inappropriate/oblique at a Hillary Clinton campaign stop aimed at entertaining.
They should immediately fire whatever moronic intern wrote this joke. Actually, it was probably DeBlasio who came up with the idea. DeBlasio is like if Big Bird and Burt had a baby and it grew up to be some annoying dope who is constantly trying to shore up his social justice bona fides.