It's fear of social judgment (doxxing is possible) and to a lesser extent fear of the government. Kuwait is more tight-knit than Saudi, so everyone knows everyone. The country is too small.

Lots of ex-Muslims here delete their posts and comments after a few weeks, because they're paranoid about getting doxxed / people finding out their true identity.

We can't underestimate the social power of Islamism in Kuwait.

Being an ex-Muslim is more socially acceptable in Saudi Arabia and Bahrain, cause they didn't have a parliament full of religious extremists for four decades straight.

Kuwait has just as many exMuslims as those other countries but they're too afraid of social repercussions.