Thinking about the claws that iquanas have, it's actually very fortunate that the iguana chose a guy wearing a helmet to hitch a ride with. Otherwise that poor firefighter might be getting stitches to repair what a frightened iguana could do, just accidentally.
I have a hunch that the free-roaming iguana might have started the fire too- not on purpose, of course, but he might have moved the heating pad to where it contacted flammable materials.Uncaged & unsupervised large lizards in a home are an accident waiting to happen. They have also started fires by knocking over heat lamps.