User blog comment:James12708/Why Exactly is Sheperd on Earth if Arrival Wasn't Completed/@comment-4967682-20121202110330/@comment-4950455-20121202212824

''what I do consider lazy writing is the fact that he gets away with working for Cerberus in ME2 way too easily. ''

I think it's pretty much explicitly established that the Alliance has a lot of 'wink-and-look-the-other-way' going on with Cerberus.