Tenure is only supposed to protect professors from the backlash of unpopular opinions, not sheer stupidity ;-)
Well, we only have seen one comment in a vacuum. It might be possible this is the only stupid thing he has done, or he might have a track record of stupid things that have not gotten him fired before. I expect he will be a guest on The View" or "Anderson Cooper" or the Shepard Smith show soon. Maybe he stupided himself into a new lucrative career.
The guy was never a professor, an associate professor or even an assistant professor.