While I agree that what she did wasn't classy in the slightest (and probably indicates a serious personality problem/personality disorder), I also agree with the idea that blowing up her entire career seems...a bit much. Imagine if both of these residents had been attendings, and one was in the process of switching jobs after having been sanctioned somehow at some hospital. The attending sending the letter might have been 'disciplined' somehow - hell, he/she could/should/would have been canned - but it probably wouldn't have been a career-ending act. We 'rehabilitate' doctors who IMHO have done far worse things (operating on patients drunk, DUIs, serious errors/demonstrations of incompetence, etc). Hell, it's not hard to imagine that in the right circumstances this resident's actions could have been hailed as 'upholding the profession' or whatever (the state boards seem to really like the idea of physicians anonymously squealing on other physicians, don't they).
As far as personality disorders go...yes we have a massive problem with this in medicine, and I agree something needs to be done about it. However, if we just tossed out every doc with a personality disorder/'personality problems' etc, I think we'd be left with a lot fewer docs than everyone seems to think there'd be. I guarantee Dartmouth has a gaggle of unpleasant cluster B types in high places - probably even in the surgery department.