It was a general assumption, and apparently not an accurate one. I don’t presume to actually know how you think from one comment. There are dog whistles on all sides, because it’s essentially a term for an “inside joke,” minus the humor (usually). It comes up most often with Nazis and racists not because they’re the center of attention necessarily, but mostly because dog whistles are needed primarily by groups that are not socially acceptable. You cannot be openly racist except with other racists, or openly a Nazi except with other Nazis. Dog whistles allow people to declare allegiance and signal to others that believe the same without needing to openly state it. Usually, we still know anyways, but it gives them plausible deniability in their eyes.