I don't know if mike would have let him live because at that point he was so paranoid. I'm not saying Fredo didn't do anything wron but its not like he wanted his brother dead. Fredo was a dumbass but he was a good guy at heart. Now a guy like Carlo on the otherhand deserved to die since he beat women, and basically was an accomplice in murder knowing full well that Sonny would be killed. Fredo didn't know it was gonna be a hit. Stupid? yes Premediatated? No