While it’s probably wrong to speculate in this direction, I do know that stable fires lead to insurance claims and horses are very expensive. That the arsonist is connected to the stable owner in any way whatsoever gives me pause, as I’m sure it will for the insurance company.
You believe or suppose that the arsonist conspired with the stable owners? If that is true you surely know nothing of horse owners/keepers. Every horse person knows how much horses fear fire. I cannot imagine one who would fire a stable full of horses. You, Sir, are sick.