Honestly, I would have to look again to see if it was. Yes, it works on assumptions, but also how intelligence is determined, and tine frame of that life. Also, intelligent life doesnt mean that it is space travelling either. Just that life is probable on more then just our rock.
As you post that and dismiss it because it was "developed in a shack in W.V". I dont see how that is relevent? Innovation, or statistical equations dont have to be developed in a sterile lab or in an office. They happen everywhere, and anywhere.