Way too far between the lines...
You wrote: "The question of spontaneity is "What started the fire?" Whether a furnace next to "a man" (unreferenced) was absolutely "impossible" to have started combustion is irrelevant. The furnace must have been demonstrably non-functional at the time of the accident for the cited conclusion. Why would one be messing with a furnace that's not working...to start it perhaps?"
You've made too many assumptions:
Who said he was working on the furnace? It was only stated that he was near it, and "near" is a relative term anyway; if I lived a block off the ocean, then it would be accurate to say that "I live near the ocean". He may have been ten feet away from the furnace, going through some boxes. Who knows?
Why does the conclusion that the furnace wasn't the cause indicate that it was "demonstrably non-functional"? Perhaps it was July and the gas/electricity to the unit were shut off. Or- as stated above- maybe he just wasn't close enough to it for it to be the culprit.
