It wasn’t arson. It was a Back Burn.
A properly run proscribed burn doesn’t “destroy property” either.
Witnesses testified that one of the fires was set by the son to cover up illegal deer slaughter and they then called BLM to falsely report that a “controlled burn” had gotten out of control.
The other back fire was set illegally during a period where there was a ban on such fires due to conditions that made them unsafe.