You also neglect the detail that the police response was of little consequence as the hacker had committed suicide before they police was at the scene.
I'm unsure what the web panel remark can mean concretely, exactly what did the children at Sandy Hook Elementary do to cause a "blackout"?
Also, of the 12 deaths wikipedia reports as "contributed to" by the blackout, one is someone falling off a roof while trying to break into a store, and another is some guy taking the stairs and dying of a hearth attack.
No other US blackout listed on wikipedia mentions any deaths, including the article about the 1977 blackout with widespread looting, but I'm sure you have a good reason to say deaths are frequent.
For an analogy to be helpful it crucial that the two aspects being related share characteristics, and school shootings don't share many aspects with blackouts. A school shooting is highly localised, even if the location my vary; blackouts need to happen over a very wide area over an extended period of time to be of importance. A school shooting is an active act of killing, a blackout only increases the lethality of already present dangers.
Also, the concept of "negatives that legislation would attempt to prevent" describes things like racial discrimination, poor quality control of seatbelt manufacturers, improper handling of meat and chemical weapon sales to dictatorships as per your "the scale of the concepts doesn't necessarily have to match". Good luck getting much out of the analogy between the Northeast blackout of 2003 and selling weapons to Saddam Hussein.
Analogies are limited by nature. Every analogy has holes. The important comparison here is "crime/tragedy occurs" -> "legal system responds with near-random actions that may or may not prevent a recurrence of the same in the future, that subject-matter specialists claim will be ineffective".