The type of rectifier used in a hot chassis TV set has nothing to do with the shock hazard. It is the connection of one side of the AC line directly to the chassis, without the isolation provided by a transformer, that causes the hazard.

While I agree that it is a good idea to replace selenium rectifiers with silicon diodes, a hot chassis set will be no safer in regards to shock hazard whether a silicon, selenium, or vacuum tube rectifier is used!