I was on a jury in an arson case in Az and I seem to remember that to establish the crime of arson there must be an immediate threat to the occupants.
In the case I heard two cockroaches in prison set fire to their prison cell to try to cause as much damage as possible but since the cell was constructed of cinderblock and stainless steel the DA couldnt make the arson stick because no matter what the cockroaches intentions there was no credible threat to other occupants of the structure.
Just my 2cents
PS who wants to start a legal defense fund for that brave patriot in AJ? He is gonna feel so much heat he could join the marines and voulnteer for Iraq so that won't be as many people shooting at him.
Stumpy
As noted, there are unquestionably variations in the required elements of the crime from state to state. In MO, for example (iirc), an arson that threatens the lives of the occupants of a building is termed ''first degree''. The intentional burning of an unoccupied building is termed ''second degree'', but is still arson.