It probably helped that every Github Pages site started going to username.github.io. I'd imagine a variety of repositories became harder to find, which'd be noticeable at Google HQ.
Based on their reluctance to put Google Code out of its misery, its sometimes hard to believe they might be aware. :)
It's a good thing they don't "put Google Code out of it's misery". There are millions of sites using jQuery hosted on Google Code.