It wasn't armed, he was just causing mayhem by running over things. I don't think they ever said anything about him firing rounds at anything. It was at a museum, and it is unlikely that it would be ready to drive off like that. I'm involved with a couple of military museums back on Long Island, one aircraft and one military vehicles, including several tanks. Both have numerous operational vehicles, but they aren't just sitting around waiting for someone to drive/fly off in. And if it isn't being maintained in operational condition, it won't have fuel, or a battery to start it, or any of the other things required to operate. I was rolling my eyes pretty good at that scenario. On the other hand there have been a few instances of someone stealing a tank from a Guard or Reserve unit, where it is more likely that you would find one ready to roll.
She said she bought the food truck in February 2020, as a way to illustrate her luck in life.