That's right that the follower system is far from perfect but it's still really manageable to save some, of course it can be hard on a first playthrough. Probably a bit too hard.
The first option is something we should probably have tested more. I think the main problem now is that the follower is a bit slow to react.
But the stay here option is not the path we wanted to take and making the follower invincible would destroy the purpose of the game.
But we're glad you liked killing those zombies and had some fun !