These hypothetical people are getting fired because their words cause real harm to people. They encourage others to act in ways that result in (not at all hypothetical) physical, emotional and economic harm, usually to underrepresented groups who are least able to weather it.

You'd get fired if you punched a coworker, getting fired for speech that encourages others to do the punching seems like fair game. If you're in a position of influence you must measure your words carefully if you care at all about not harming people.

If you want to explore radical, potentially harmful ideas, find a safe space of like minded people to do it in rather than forcing it on random people on the internet unconsensually.