I'm actually not sure at all about the law but I would expect to get a visit from law enforcement eventually.
In the risk-benefit analysis, let's be sure we consider another factor: Unknown, unpredictable, armed, nut-job third parties who are triggered to act — sometimes in concert — when dog-whistle rhetoric goes viral.
Depending on the circumstances, a prudent analysis might limit 1A protection for certain types of rhetoric because of its unacceptable risk to others. That might be the case even for facially non-violent speech, e.g., so-called dog whistles.
It's been said that the Constitution is not a suicide pact [0] — neither is it a license to kill.
[0] https://en.wikipedia.org/wiki/The_Constitution_is_not_a_suic...
Courts are up to the task — it's Con Law 101.