Calling it dog-whistles instead of calling out specific issues with the argument implies that the problem isn't what he is saying, but that he is saying things

Calling it dog-whistles instead of calling out specific issues with the argument implies that the problem isn't what he is saying, but that he is saying things that sound like things said by other people. IE, calling it crypto-fascist dog whistles is saying "I think he is a fascist because he says things I think fascists say, but isn't actually coming out and saying fascist things". Which, in the end, means that no one can say things that fascists might also say, without sounding like a fascist.