For those who have experience flying with service dogs: Wouldn't the fact that he needed special accommodation for his dog have come up when he purchased his ticket?
The service dogs I've seen are very well cared for (not to mention among the best trained dogs you'll find). Given some of the people I've had the misfortune to be seated next to, I'd much rather be next to one of these dogs on a flight.
Tell the pretend pax they are there for another reason, like testing the onboard entertainment features, then spring the evacuation drill as a surprise. The financial incentive is interesting, but could lead to really bad results.
"He had filed plans to fly to Pelee Island on Lake Erie, a route he had flown multiple times." Plus, "...the man notified authorities when he landed on the island hours before the crash, but did not mention another trip." At the very least, sounds suspicious.