1. This drone does not fit the description of any known DOD drone, so you should assume it’s classified. The DOD is meticulous about only flying classified aircraft in restricted airspace where they can prevent prying eyes and inadvertent attention. Tucson is not immediately close to any of the usual hotspots for classified aircraft (Area 51 for example).
2. The article describes the drone buzzing the original CBP chopper as well as flying an orbit around the police helicopter. It is reasonable to suggest that a collision between the drone and either of those helicopters would be fatal for the pilot. No military pilot I know would ever create the type of risky scenario as described here.
3. Classified and unclassified aircraft are not just operated by a dude that hops into a plane or sits down at a drone console. They’re planned out. They’re also not operated in a vacuum. If your scenario of a classified drone operating in this airspace were true, and the drone was picked up by a friendly chopper, the operator would most likely immediately land safely and have someone reach out to the pilots and let them know not to mess with the aircraft. They would certainly not go rogue and risk a major accident or fatality.
4. I consider it highly unlikely the DOD would ever use other agency resources to unwittingly run training Ops. That seems like a career-ending move.