I couldn't read the linked post because it doesn't like my adblocker. As you've described it, it doesn't keep you from comparison shopping at all, it keeps you from comparison shopping using Amazon's property, i.e. the free wifi they give you. You can still use cellular service or another wifi to do your comparisons. It seems pretty reasonable to me that if you're in an Amazon brink and mortar store, and you're using their wifi, they can control what websites you're allowed to see. Don't like it, thanks to the free market, you can use another provider for internet connectivity, or you can shop somewhere else.
RE: Amazon has a patent to keep you from comparison shopping while you’re in its stores June 16, 2017, Washington Post