Take the chart of the Dow short you posted earlier. The screen shot is around the low of the day. When it started to reverse back up - what did you think? As you watched price creep towards b/e and your nice profit gradually eroded away - what did you think then? If you were sitting at your screen with your fingers crossed, hoping and praying it would reverse back down - then you're likely to be disappointed with the outcome more often than not. You need to be prepared for that to happen. Indeed, expect it to happen and have a plan of action for when it does.
A hedge is just one possibility. You could have neutralized the effect of the reversal back up by taking a long position on the June future (SB firm's version of the YM). So long as IG's spread isn't silly (and they can be with some SB firms - e.g. 6pts with Cap' Spreads!) you'll lock in some profit - no matter what price does. Try it. It might not work for you: you might not be comfortable with it. However, at the very least, it should help to cap how much you lose.
I don't see his problem as watching the trade turn into a loss, losses happen and have to be accepted. To me the two main problems were he shouldn't really have been going short, and he shouldn't have been trading at a level that would blow his account. I think he needs to address his MM and strategy before considering a hedging strategy, - as hedging can also be costly and complex.