I think this is a more realistic projection that accounts for... updated modern understsnding of how long radiation persists in nature, as well as... there aren't as many nuclear weapons as there were at the height of the Cold War, and those nuclear weapons are now more spread out against a whole bunch of other nculear powers and targets around the world...
So... if you're in OK, you could maybe stand a shot at avoiding a massively irradiated area if there was any warning?
Or, a reasonable shot at only needing 2 weeks of food and water to shelter in place and ... at least not die of radiation poisoning?
On the other hand, FEMA barely exists, and the Post Office is fucked... so that would cripple the older triage and rebuild plans I am aware of from the Cold War.
All the old postal carrier vehicles were supposed to be turned into makeshift ambulances...
...
But anyway, just a general 'lol' at all the ICBM sites in the great plains getting at least one if not several nukes likely dedicated to them, each.