The problem with that problem is you can say any kind of accusation of racist behavior is non-falsifiable in the same way (“You can’t prove I was shitty to them because they were black, maybe I was shitty to them because they’re just a jerk”), but everyone knows racist behavior and dog whistles still exist

if people buy the claim

This is a good demonstration of why the concept of dog whistles isn’t really a problem, because when it’s a totally absurd accusation people aren’t going to buy it.