The Acura TLX has LED headlights, no bulbs to replace.
Perhaps the car was an Acura TL, those have HID headlights that operate with a very high voltage. If a headlight bulb connector is left loose with no bulb connected there will be sparks jumping across the connector when the headlights are switched on. The question is what did he ignite? A rag near the connector? Cleaning solvent?
I have been working with HID lamps for 15 years, I have never witnessed a fire caused by a headlight repair mishap much less to set fire to a building.