You missed a few steps:
Step 1:Google seeds a randomized word and associates a link for that word into their search engine.
Step 1.5: Google employee installs Bing toolbar
Step 2: Google employee searches Google for that word and up comes the random link
Step 2.5: Google employee with Bing toolbar installed generates fake user click data showing that a user searching for that randomized word then clicks on the "random" link
Step 3: Google employee searches Bing for the exact same word and up comes the same link.
The bolded steps are the only really relevant ones here. Bing is responding to falsified click-stream data (which is the only data for that randomized word) by promoting the particular link in its search results for the randomized word. The fact that Google returned that particular link in its search results is almost entirely irrelevant to anyone who's not trying to confuse you into believing Bing is "copying" Googles results.