"There would seem to be little doubt that the black faces of the traditional morris dance groups of the Welsh Border counties were at least influenced by minstrelsy. The occasional use of banjoes, bones and tambourines in these morris dances cannot be mere coincidence."
I have danced Cotswold to musos playing banjo, and tambourines - although I'm not sure about bones - spoons, though. Does this mean I'm a racist? (and guitar, ukelele, flute, recorder, even a tuba...)
Dance sides of all shapes and sizes have used whatever instruments and musos were available.
The above quote, however, is simply opinion ("would seem..." "cannot be...")
It is perfectly possible that banjoes were popular at a given time as a result of minstrel shows. But someone who has learnt to play banjo as a result subsequently playing for a morris side doesn't provide a very convincing link to racism, intended or otherwise.