I've registered the username. Not one person under two accounts. I'm sure the brojos would be happy to check IPs if you're really that upset about it.
And you know, you're right -- a lot of this is, at a "fundamental level," physics. But systems get too complex very quickly to use "just physics" to study things that biologists, chemists, etc. study. So that's why I take issue with calling it "just physics." No one can use "just physics" to predict how fast someone is going to run. Also, it's strange to pay lip service to physics, and then claim you know the answer about how fast she's going to run because (as far as I can tell) you haven't actually done any physics here. People who study this area, like physiologists, sports scientists, chemists, track/XC coaches (some of whom, you're right, do a lot of physics!) would have trouble telling you exactly what type of shape she's in given her blood work and lots of other data (which none of us has).
Most people in this situation, as you've seen, appeal to experience because that's the best data we have to compare to the data she's given us. In my experience, when I was roughly in shape to run her PBs, I could not have run that workout. But I was more of a 1500 runner. So I'm excited to see how fast Natalie Cook runs in the future.