The weird thing here is that a cashier would test it!?
It wasn't confusing to me, but evidently the way it was worded confused others.
"Some cash has cocaine on it" has no logical relationship to "all cryptocurreny use is illegitimate".
If they wanted to refute the original claim and say that cryptocurrency has legitimate uses or if they wanted to make a separate point to say that cash is similarly only useful to criminals, they failed.