AFAICT, MBS himself is not a religious extremist, just a power-hungry tyrant who doesn't tolerate dissent. There's a difference. The dynamic has long been that the royals running the place are much more liberal than the Wahhabis who enforce the religion, and have slowly been trying to liberalize things. It's another great example of why democracy isn't some kind of silver bullet that will magically make populations accept socially liberal values. If Saudi Arabia lost its monarchy and became democratic, it'd be even worse than it is now.