Yes, that is preposterous. Let's assume for the sake of argument that it's true. The people who promote the theory seem to be the only ones capable of hearing

Yes, that is preposterous. Let's assume for the sake of argument that it's true. The people who promote the theory seem to be the only ones capable of hearing this whistle, the theory itself being political backlash, so it clearly defeats its own purpose in that regard. And of course it does nothing to prevent backlash from the actual policy goals. It's simply an attempt to get away with arguing against straw men. Taking a perfectly reasonable statement, such as "enforce established immigration law" and take it to be "code" for something completely indefensible like "keep out those subhuman spics". It's hard to argue against the former, much easier to argue against the latter. Of course it does nothing to change the mind of your opponent who already knows and agrees that people of any given ethnicity are not less than human, but it does prevent those in your own camp from taking anything your opponent says as a reasonable statement. Scott Adams described the phenomenon in a recent blog post: http://blog.dilbert.com/2018/06/10/why-democrats-hear-a-secret-racist-dog-whistle-and-republicans-dont/ http://blog.dilbert.com/2018/06/10/why-democrats-hear-a-secr...