It doesn’t merely mean it’s ok to target Zelensky, it’s a nuclear red line. It would have justified thermonuclear attack up to and including extermination of major cities. If the Ukrainians did this then by al
means cut them off. If Western regimes won’t then it’s time for western regime change, not just Zelensky.
It might trigger such an attack--although I doubt it--but would not justify it. Anyone who thinks so is insane.
Putin started the war. Zelensky did not. Russia invaded Ukraine - not the other way around.