Me too, doing it for a living has taught me a lot of lessons. If he has a vendor's licence then you're definitely a business. Hopefully he was insured. Then there will be coverage for the damage done to his home in the fire.
If it's insured only under a homeowner's policy, we need to stay tuned. The most common homeowner's policy in VA excludes other structures used at any time for any business reason, and limits business personal policy, severely. Some exclude coverage if any liquid or gaseous fuel is stored there. The adjuster generally sends a coverage analysis up the chain, and an examiner may note that and come right back down with a hammer.
I assumed Syke had some sort of commercial coverage and still hope he does.