PC to say "must be a f'in white guy causing problems"?! Some may be granted greater license in the way they refer to others, but I don't think that makes the expression "PC," and I am certain it doesn't make it right. I expect, though, that most of us understand the context of what the OP recounted. At least he was on the safe side of that wall, not in a subway car or other less safe environment encountering the same sort of thing.

(Maybe the construction crew was just working on a rap act that will see them one day rich and famous as idolized performers. I'm too culturally out of it to know whether they would have what it takes to succeed.)