I don't want to discount the validity of your question -- it's a legit question, after all.
But I do want to put forth the following observation: systems to organize society can't be dismissed on the basis of ultra-extraordinary situations. There will always be a "what if" that no system whatsoever can address properly. The system is not a recipe for 100% perfect harmony and cooperation, and one made-up hypothetical scenario that is very unlikely cannot be used to say "See? Your system doesn't work". Just like the statement "man is a biped" cannot be proven to be false by saying "Imagine men coming from war without legs. See? 'Man is a biped' is a lie!".
This, I think, is a thought that quite often gets lost in the frenzy to "prove" that this or that system is "bad" or "unworkable".
On the other hand, systems to organize society can and should be judged on their usual performance. And when you do that, you'll gain a new disrespect for political systems. Look at the miserable failure that are the contemporary "justice", "legislation", and "law enforcement" systems. Look at how horrible these systems are at resolving human conflict; they are so shitty that people actively avoid or dread resorting to them. Look at how many people were slaughtered by their own rulers in the 20th century: 270 million human beings. Resist a man in a blue costume because he is being unjust? Chances are he'll kill or maim you, and blame you for it.
When you see reality over thought experiments, it becomes pretty clear that pretty much any other system (save perhaps for mass and total suicide) can dramatically improve these criminal disasters that are ruining people's lives right now.
So, honestly, who cares if voluntaryism can't "solve" the "Mary Typhoid" problem? At least I know voluntaryism won't cause the mass murder of 300 million people, and marginalize / gulagize more people than that. That is strictly better, and I'm pretty happy with that solution to human conflict.
Your house is up in flames and you're asking me whether my firetruck can put out a lit match. Maybe let's focus on your house before it crumbles in ashes to the ground?
That is my humble view on the subject. Thanks for your question, it is appreciated.