Mafia 111. Buruaka

Did the Mafia get scared of Master-Balzac's block and start killing with the boss?

It seems like they've had this strategy from the beginning – killing with different roles. I don't think it's related to fear of anything.

Why wouldn't they block the blocker and calmly kill with Balzac?

Who said they know for sure who the blocker is? And I don't think that's what happened in the end. They went to kill Gorio with the boss, and Balzac was checking, just to be sure about the townie's role.