What do you think it would be? I think my favorite fan theory is he is a war veteran.
• He references a truckload of soldiers being blown up as "part of the plan". Could reference vengeful thoughts towards a politician treating soldiers like pawns.
• Extensive arms and explosives knowledge including rigging remote ones.
• Seems to understand how the system works and trolls it.
• No identity could mean he was a part of an elite military squad.