I was just wondering: how could it be that even in a government led by an infallible, Ahlul Kitab aren’t executed but Muslims from a different sect (namely, Alawis) are?
Also Wahhabis aren’t to be killed but, again, Muslims from another sect (Alawis) are?

There are different branches of Alawis. Assuming they would be executed, only those who openly state Imam Ali is God would be executed. That’s because they are no longer Muslims for saying that. When you say: Imam Ali is God, you are not longer a Muslim. You would be a kafir and so not protected by the law. Now you could argue: well Christians also say Jesus is God. Yes, however, Christians got confused in history and they were led to believe that Jesus said that.
But Imam Ali himself while alive would say: I am not God. That’s blasphemy. I am not God and I never claimed that. I am a servant of God. And then the Alawi comes and says: no you are God. That’s just pure stubbornness and deviation which cannot be justified in any way.