Now do sale of region-free DVD players in the U.S.

In any case, it’s perfectly legal for me to make and sell a geo-locked device in another country, and it is the importer’s problem if fails to work elsewhere. That doesn’t tend to happen with physical books, obviously.

Post-sale disabling of inverter devices is different than lack of support. The Supreme Court case on textbooks arose from profits on textbook arbitrage. New device-related caselaw will depend on a plaintiff that makes enough from device arbitrage to fund a lawsuit.