He lives in and broadcasts from Palm Beach most of the time. I think he has an apartment in NYC and occasionally broadcasts from there. Under NY stringent tax laws he is probably considered a resident because he spends a certain amount of time living and earning there...?
He’s probably considered a resident because he had a residence and place of business landed there (the broadcast booth).
But while Rush has opposed such “tax the rich” laws, the Rolling Stones and Beatles have espoused more Left Wing rhetoric and yet both have engaged in “offshore” tax dodges to escape higher tax rates. Help was made in Bermuda to avoid British taxes (they had to be out of the country a period of time to save their earnings).