While I have no beef with a 'fresh out of training, first day on the job Superman' being put in an impossible situation where he has no choice but to kill Zod, the way it was done in MoS wasn't an impossible situation.There was nothing thoughtless about Zod's snapped neck.
He has Zod in a headlock and Snyder is telling me Superman couldn't have simply just moved his head away from those people? He couldn't have put his hand over his face to block the blast? He couldn't have wrestled Zod away and told the family to run while there was a chance? Maybe he jumped the gun and killed him due to the lack of experience, but that seems like a stretch.
I find this a lot with Snyder movies, I get what he was going for, but I always find the execution lacking.