If he wants to go through transmissions, why does it matter to everyone else? The Z is meant to be driven, let him drive it how he pleases. Its not costing you any money.
Hopefully you can find some setup that will keep you drag guys from going through transmissions like diapers. Good luck getting your times down, Greg also.
Ignore the haters, what you are doing is respectable. Keeping it on the track and setting goals for your Z is nothing to be ashamed of.