hypothetically, what would happen if you kept the TV, leaving it unopened for a month or so (so you can be sure nobody wants it anymore), then used it yourself?
I don't know but people do it all the time when receiving large quantities of narcotics or merchandise paid for with stolen credit cards. You write "return to sender" on the parcel and leave it unopened by your front door. Sounds like a bad urban legend akin to "if you ask an undercover cop whether they're a cop, they have to tell you" but plenty of people still do it.