Tower wouldn't even NEED to pay him. All he has to do is roll up to the The Hedgehog household and tell him "Eggman's gone too far. We're going to ice the fucker." and he have Sonic PLUS some of the former FFs with him.
Heck, if you want to make him a secondary antagonist? Just have him verbally threaten Amy and Amethyst, this shock collar shit is just plain OUT OF LINE even for Tower.
I say all that, but I'm remembering the first time I saw GUN in the City Escape. Gigantic Truck rolling all over suburbia trying to Run Sonic over.
This organization has never been sensible.