Maybe it's just me, but a more logical move is to leave the light off and dial 911. Rowdy kids or whatever, not a bright move to let them know that you witnessed it. Besides, if there was a glow inside an empty, unfinished house, someone should investigate it.
“he calmly turned around and walked across the park.”
Seems that Jack would have returned to his house.
I agree with you, but I'd bet alot of folks think turning a light on is a way to scare bad people away. It's too bad, because if the "firebomber" had been apprehended at that time, Jack Wheeler might still be alive.