As I stated, I really don't have the expertise to judge the accuracy of his facts, not of his interpretations. No doubt there are many nits that could be picked. This was a minor part of his thesis, however, and not necessary for the foundation of it to stand. Also, he had some evidence.
Read it for yourself.
Would be interested in reading a survey of what the actual archaeological evidence from this period indicates. I am somewhat skeptical of authors desperately trying to find evidence for their theories, rather than developing theories based on the evidence.
It seems clear that the big agricultural operations fell apart at roughly this time. There are two likely reasons, most likely intertwined: collapse of the transport mechanisms for getting large agricultural surpluses to market, and collapse of the market due to cities losing their population.
There is no point in producing much larger amounts of grain than can be consumed locally if there is no way to get it to market, and nobody to sell it to when you get there. And of course a trade in bulks such as grain can’t exist without both a good surplus production in one area and a good market in another. And cities can’t survive without a market for their products and a source of food to feed them.