Because that thread is not funny or vaguely clever, it's a childish attempt to mock people for showing caution and vigilance. One post was out of order (I suspected it was another joke, albeit one in bad taste) and it was deleted. I do not see what other unacceptable racist comments there are here. Wrong address? As I said, maybe. But you don't know that. There is chance it was something else, hence the original query. The OP was no more racist than it is sexist, ageist, or anti-cyclist.