Fourthly, a virus on a smart meter? Good luck with that. They're nowhere near that smart...
What an incredibly naive assumption. A friend of mine audits smart meter security and occasionally speaks at Black Hat about them. Viruses can target embedded systems and can be written if the flash/update mechanism over the network is secured with "childishly simple" methods. Once compromised firmware has been distributed across the network of meters, if they happen to have a remote disconnect feature, hundreds of thousands of houses could be potentially disconnected from the grid simultaneously at the command of a malicious hacker.
If that much of the load was removed from the grid at once, permanent damage to the power infrastructure can occur, about as devastating as an EMP attack to a city. All this because the utilities are too greedy and don't want to remove the remote disconnect feature from the meters.
Remember, anyone can get a meter and perform all sorts of reverse engineering. Is it really secure when you think about stopping a persistent threat with the skill and resources of the stuxnet authors. Some technology professionals see "childishly simple" security to be professional malpractice, like failing to perform basic load calculations when designing a bridge.