Start by blacklisting everyone from russia and south america ...
Dunno what you mean by exploit here. Is giving away bought keys that wrong? If nobody wants this game - nobody enters, it's simple as that. No 5 entrants, no CV points. Yet, over 600 people entered to get it. It was in my wishlist and I won it today the same way and I don't care how much someone paid for the key he gave me. It works the same way for my GA. If this will get bundled - that is the risk I and everyone else took as well. It works for every title on sale or bundle (strangely not with humble monthly ... well, I can partially understand it). But lets go back to my first words. Regions I have mentioned have way lower steam prices than I do (actually, in most cases your prices are lower as well, but CV is calculated using your price ... so should I say that you are exploiting as well?). Their webshops with steam keys have even lower prices, yet those are not registered by SG. Their region restricted sales are uber-cheap yet they still get full CV. So what? All RU and SA restricted GAs should be considered as exploits maybe?
If you want, then buy those same keys and create your own GAs, to make more ppl happy, that they could actually win something.