Seems to me that everything depends on the intention of the speaker. In the case raised by the OP, it was (as I understand it, having not watched the show) very clear from the initial context that the word was being used in a friendly ‘ironic’ way, between two people who were in fact the two closest mates in the house - and was understood as such by both of them.
As one journo commented, a case of a middle class white girl who’s listened to a bit of Eminem and is trying, perhaps a tad ineptly, to ‘be street’. ‘No offense; none taken’ seems the only grown up response...except of course by the production company who, after the earlier incident with the Indian woman and wotsername, erred understandably on the side of caution and pushed the Big Red Button.
I would personally never dare to use the term, for fear of getting it wrong. But to deny it to entire races seems to me bizarrely close to racism. (En passant, I got chided on another board recently for using the term ‘Irishman’.)