Bah, that's easy.
Option One -- He wasn't killed, he's part of the plot, he was a CIA plant who pretended to be part of the CT community, simply so that he could be "killed" and make it appear like yet another government-created "disaster" was real. We have people who've spotted someone who looks suspiciously like him working on a farm in Kansas. When they approached him called him by name, he acted confused and pretended he was someone else...but that's what you'd expect him to do, isn't it?
Option Two -- The overall disaster was a government-staged scam, and most of the people who "died" were just NWO agents who were subsequently assigned new lives. But our man was getting too close to the truth, so they used this incident to actually kill him. This is incontrovertible proof that the government is afraid of us, and that we are getting too close to the truth!
ETA: Then, of course, CTers would split into two separate factions supporting each theory, with the latter accusing the former of being either mindless sheeple, or of also being NWO agents.