Brilliant, this has got to be the best idea to combat hacks and exploits in multiplayer I have seen in a long time!

Cheaters get delegated to the cheaters pool where they basically have an "open sandbox" to play with their hacks. Rockstar keeps an eye out for new hacks and exploits used in the pool, release a patch to fix them, then just wait for new hacks to surface in the cheaters pool. Just rinse and repeat! :-)