If you read the material kicking about from real doctors about this you'll see it's not the case.
It's fairly short term damage: in the long term he's going to see lots of benefits :) (edit: im not sure you could even call it damage, thety are just "flesh wounds". I bet some of us here have worse RSI from sat typing all day!)
The human body is incredibly resilient and it is often truely difficult to really seriously damage it in the long term.
He is overtraining. From the article it sounds like he may have stress fractures already.
Hell, I'll just forward this article to my athletic trainer and sports med friends and see what they say, and post their comments in a followup post.
People racing to the South Pole regularly screw their feet up (with blisters, tears, ripped nails and all sorts) within a few days (or even hours). The foot is quite easily damaged and just as easily repaired :)
As to ligament damage I dont really know because Im not a serious "trainer" but I do cycle regularly and ligament damage I have done in the past has healed in a week or so.
On the other hand after a month or so of not cycling (say on holiday) I find a week of intensive work is great for retoning your body. This sounds like the same - just a little more extreme.
Top ten reasons not to run marathons: http://www.arthurdevany.com/2005/08/top_ten_reasons.html