We know franz is a pretty cunning fighter from the very start of thes torry and his first fight with Humongulous. So that make sense. Not sure it'd work so well thoI'm expecting Franz to run back in with the door or a chunk of pillar and slam it down on top of the FSMADD. He can't fight such a clank without a weapon, at least not without his fire
Also note than when talking about his flamme earlier he says "I'm at low power". Sounds like a good set upp for Franz to use the Iram Solus at some point...