I am well aware that it is not the first recourse. But most of those other methods will not completely eliminate it, especially if facing hyper inflation. It would be illegal but it would thrive just like alcohol or drug under various prohibitions.
If such a situation occurs where the currency has already been deemed illegal and is purely an underground thing in a "communist utopia" the a 51% attack might be resorted to simply because there is no defense against it.
One thing that's for sure if they try to pull of such a stunt is that they 'll realize how annoying pre orders are