He created Illuminator to fit his character and personality. He ran Screamin' Demon originally because that's what he bought off of Gary Bauer, the original owner and creator of Screamin' Demon. But Jay wanted something to fit him better, so he went with a new name to fit the new truck to his team (which was the old Virginia Giant #3), being Illuminator.
And in case you're wondering, the Screamin' Demon name is now owned by Kevin Mileti, who also plans on getting a completely new truck built so he can run the name again with fresh equipment. And the original Screamin' Demon got an overhaul with a new cradle and some roll cage redesigning, which was done by the team at Badlands Off Road Park out of Attica, IN. They now run the chassis as Park Patrol, one of two of their own monster trucks.