Minstrelsy dates from the 1860s, so considerably pre-dates Sharp.
Anyway, times change. Guy Gibson did call his dog 'Nigger', and my grandmother would take of 'nigger brown' paint, but that is unacceptable today. Just as it is unacceptable to call a Jew a 'yid', or to call a Catholic a 'a Romish whore' or a chinese man a 'chink' or...
But you get the picture I hope.
Times change, and a largely re-invented 'tradition' like border morris should similarly be open to change. To cling on to an ersatz 'tradition' is stupidly stubborn at best and downright offensive at worst.
An to those who whinge on about political correctness, tough shit if it means you actually have to engage your brains before opening your mouths. If it's PC to stop using words like nigger, yid, poof, paki, pikey, queer, darkie, spaz, coon, jewboy, mick or whatever, then praise be for PC.