It isn't supposed to prove anything on a rigorous scientific level. This is just something I live with day in and day out. People shit their pants in fear of not being optimal. Screw optimal, eat a steak.
Now that my rant at the masses is over, I totally agree with what you are saying. There are major studies done on this sort of thing with people who have lots of money and equipment at their disposal. This was simply an attempt to show that the idea that your body implodes if you get more than a very low amount of protein is false. Can I prove it with peer reviewed double blind studies of over 100 participants who are also athletes? Not really. But my traps will support my conclusion
It is a good discussion to have, in particular because I value science and rigor greatly. I studied chemistry and mathematics in a past life before I sold out and went the route of computer science, and I have a soft spot for a good study and quality research. But every now and then a little bit of anecdotal evidence on a topic that has been blown way out of proportion is a good thing. With words like metabolic damage, optimal protein synthesis, de novo lipogenesis, and all natural anabolic amplifier being bandied around by people with heavy hitting advertising departments, this is an attempt at a return to sanity, with some numbers for the generation who can't actually read or comprehend them, but requires numbers and charts before they believe anything.