Zombie's taunt does change your target selection during auto

It is WAI. That means it's working as they want it to work. It has nothing to do with how you want it to work.

I disagree fully with your last sentence. If auto isn't working because of game mechanics, don't use it. IMO auto should only be used if you are guaranteed to win with it on, or you need to beat the clock. Since neither case applies here, don't use it.