the only problem is how is he to do that? What operating system does it use? What method of installation would work, i.e, is it a firmware operating system(more than likely) which would have to be "flashed", if it has application capability, this may make this easier, but then the anti-malware would perhaps need to work on an ARM processor - for example.
There are so many variables here, that it is a daunting task. I'm not even going into the fact that a firewall is probably a good idea, although the malware may not need to communicate in a way that would give a firewall any kind of successful function. Malware is already able to function completely under the radar on regular PCs, as they don't need permissions that would signify any kind of behavior that would set off alarms, alerts, or heuristic intrusion detection systems. There are HIPS capable of blocking such behavior but they are only written for Windows operating systems.
Perhaps the best bet would be a mobile version of the AV/AM that are written for Linux distributions like Android or Apple's iOS for example. This is assuming the TV uses an ARM processor though, if not - you gotta lotta questions that have to be answered before learning if this is possible - short of writing the open source code yourself.