To be honest I never knew direct linking through a hoplink was against Adword's TOS. Then simply use a PHP redirect on your own domain. It's a bit of code that you have to use. i.e http://www.your-domain-name.com/earth4energy.php Google it : php redirect and you find exactly what you need to do. Another way is to redirect your own domain through your affiliate link. Only 600 hops from 70 articles is pretty possible, it depends on what keywords he managed to rank his articles if they have been ranked at all. It's horrible anyways you just got one sale out of 70 articles which them alone are worth at least $350.
Khan12, What you have described sounds to me to be 100% correct. I am very familiar with what you describe and indeed the same thing happened with truthaboutabs.com about 3 months ago and about a year ago it happened with fatloss4idiots.com. Google does not have any issue with direct linking, your ads will simply show according to the single display url rule. This means that you will be in direct competition for placement with anyone else trying to direct link - this has nothing to do with any slaps.