Using a propane burner that's specifically designed to only be used outdoors inside a basement? If your insurance company's not going to deny that claim, I want all my coverage through them but I can't imagine that's the case across the industry.
Using a turkey fryer on a deck? That's something a reasonably person would do. You're outdoors, after all. Too close to the house? That's an understandable mistake, as is leaving the stove on when you leave the house (I've done that myself, burned myself a little bit last week because I had left the stovetop on).
Using a outdoor propane burner inside a basement? Whole other thing, that's easy to perceive as well beyond stupid and well into the realm of willfully negligent. It sure as hell isn't a fight I'd want to battle in court.