CrumbSnatcher has hiked the AT three times that I'm aware of, so he probably knows what he's talking about. Perhaps you're taking him too literal and he meant most haven't hiked long distances prior to starting the AT, for which I'll agree.
Also, if I'm not mistaken he was responding to this, and not the OP
And although he may be grumpy-at-times, I don't think he's an old man, or looks down on anyone.