And yes, ignoring nasty history is dog-whistling. You can say certain things, which are clearly perceived as racist by racists and the offended, and then avoid responsibility by claiming "it's only because the history".

Example: It's not antisemitic to blame George Soros (a jew) for political influence through his money, except that there is a broad and infamous history of such conspiracy theories. Same for "dual loyalty".

It's not racist or insensitive to use black-face as a disguise, except for the long history of mistrel-acts of making fun of Afro-American (slaves) for being lazy, uncultured and stupid.

It's not necessarily racist to suspect a Muslim of being a terrorist. Hey, there may actually be valid and objective reasons for such a suspicion. But especially because of the context and the history of Muslims being accosted as such and being targeted all the time, such claims better have substantial proof.