This is not a contrivance at all. If you ignore the bad juju that has been the hallmark of the series since Alien 3 and just continue where Aliens left off, maybe a decade or 2 later then it makes perfect sense. Biehn would fit right in. If you go on the Michael Biehn FB page, you will see that he is actually asking people to support the idea. I hope Fox let's him Mickey Rourke this thing. Biehn is an acting genius and I am convinced that given this opportunity, he can shine again...