Levi's not sure if he's protecting SecUnit from the convoy or the convoy from SecUnit in case it goes berserk but it barely mattered as it worked out the same way. He doesn't think he expects monsters line in Prehevil here, but who knows. At least if anyone tried to talk to them he could default to solider-mode and tell them they have somewhere to be.

He knows the way to the sick bay, though, so it should be a quick and easy trip.