Look up what 'deciding' means. If, as you say, "...vote wouldn't have mattered at that point" it's by definition not deciding.
Besides, that woman provided a dishonest answer in itself. She said she "would have no moral objection to putting a bullet through his skull". What does that even mean? Was she going to put the bullet through his head herself? If so, why not just say that? Or is it that she won't object to someone else doing it? What if no one else had the courage? Or no one had the opportunity? All that BS instead of taking an easy route of denying Hitler power by casting a deciding vote. The more I read on libertarians' positions, the less I think they have anything in common with reality.