How about claiming you're (he's) an alcoholic, checking yourself into a clinic for a month of pampering, then get released and sue for your job back. It's worked for a number of airline guys over the years, and it's certainly worked for a large group of actors and politicians.
Seriously, did the company warn this guy after each occurance? Was a letter (or two, or three) put in his file? If not, he may have a case for wrongful termination. He should check with a aviation lawyer. Was his airline a union shop? Was he offered union representation for his firing and exit meeting? All these things come into play. However, it is a very slippery slope, once you start on the road of trying to regain your lost job. Companies don't take well to their right to fire being challanged. However, if an attorney says he has a good case, he should seriously consider suing for his job. At times, airlines have lost lawsuits and have negotiated a cash payout to the ex-employee, instead of giving him/her their job back. That would be the best of all worlds. He could put a bunch of $$ in the bank, and the company could uphold their "honor" or his remaining "fired." At any rate, good luck with whatever he decides to do.