No, it's not that Bing was redirecting traffic through Google. Instead it was that windows/IE8 was sending data on search terms/clicks on google from their user

No, it's not that Bing was redirecting traffic through Google. Instead it was that windows/IE8 was sending data on search terms/clicks on google from their users' machines to Microsoft. So user searches Google for a search term and then clicks on a result. This data is then sent to Microsoft, and Bing is updated accordingly (and will return that result for that search term) at a later point in time.