Not attacking a strawman, I asked him to clarify and then talked about the context.

"Conspiracy theorists" often look at an event that's heavily covered by the media, that serves a perceived state interest, and investigate it further. Particularly if it receives disproportionate emphasis, like the various mass casualty events that were referenced so often they're just referred to by dates ("9/11", "7/7", "Oct. 7", etc.). Sandy Hook served a perceived state interest (popular disarmament), and people perceived "weird things about it", so to speak, so interpretations of the event differed. Sometimes people try to explain the formation of these theories in terms of fulfillment of an emotional need ("they can't accept this would just happen so they need to pretend someone is in control"), which is just inaccurate. They have a mental model, whether accurate in a given case or not, where there's an antagonistic power structure of some kind orchestrating events or narratives for its own benefit, and are simply applying that lens to understand new events and narratives.

At the end of the day, it is a fact that the U.S. government does things like this in general. You look at declassified CIA documents from the past, they are very open about overthrowing governments, manipulating public perception, and all sorts of other shady behavior. But they're not open about them as they're doing them. So we're left with the difficulty of figuring it out for ourselves.