I would contend that most (if not all) “long shelf life” dehydrated/freeze dried food products fail to deliver the calorie and protein count that is required to survive. It is far more likely that you would have to double the quantity and cost to actually achieve any specified duration. If you don’t believe me, just examine the details in their advertising.
So a nuclear war would be bad, but how likely is it? Well, not as likely as it could be. This isn’t 1983; the Cold War is over. On the other hand, it could come back. Russia is smarting from the treatment we gave them during the Clinton era, and they’re steadily rebuilding their military. Russia’s nuclear forces are the most powerful on Earth, and President Putin probably has the starch to use them if he thinks it’s necessary. Putin is also pushing hard to rebuild Russia’s influence in eastern Europe, and there are several places where a small border skirmish could grow into a confrontation between Russian and NATO troops. If that happens, nuclear war is back on the table.
The Oppidum is located in Czech Republic, a region surrounded by mountains. The place was never targeted as a subject for aggression. Geographically, any possible conflict will most likely stay away from Czech Republic or invaders may likely reach it at a later stage. By that time, residents and the owner of The Oppidum will arrive and have plenty of time to prepare.