The same way that McDonald’s or H&R Block are preventing you from using a Treo 650. Those companies also do not provide cellular service compatible with that phone.
The main difference being that Verizon sold me the phone and supported it on their network until they didn't. So yes, the Treo 650 still turns on and can be used without voice or data service, but claiming that Verizon is no more preventing me from using it than McDonald's or H&R Block in this case seems disingenuous.