Most preppers are already armed and dangerous. That pretty much negates about half of these points. The author is full of sh**.
I don’t know of many preppers who are prepared for an artillary duel.
Or even something small like 60mm mortars.
If a military faction wants your resources in a war for all the marbles, you ain’t squaring off like in Bosnia or Afghanistan. You are getting World War Two or Desert Storm and they won’t give a crap if the building you were in has to be leveled or not, so long as they don’t risk taking casualties.