Maybe the line of reasoning offered and argued against is dubious. But IMO there are literally dozens of other arguments that will come to the same conclusion if you want to avoid hand waving about the particular bits the author raises.

By and large states having different laws is a pain, but arguing that you can do business in every state while only following the laws of one state is a very messy rejection of state's rights, and leads to using the commerce clause to basically negate most state level regulations and jurisdiction.