That is the problem that anyone who tries to do a direct hedge against an intra-commodity spread using current and forward months will have. In the case of NG, which is traded 12 months of the year, sure, you can just go long on front month and short the following month. The big issue there is that no matter what happens, the two/three/four/five months in the future move in sync, so you will always be effectively net zero.
Perhaps the guy pulled the plug on his long leg and hoped for the market to keep going down. So he closed his longs with a huge losing monetary value. But he was so deep into his shorts that when the contract rolled, and so many OTHER shorts HAD to close to either reduce losses (like he may have done) or lock in profits, the thing went to the moon in a day. He then got margin-called on his shorts, so he was "short-squeezed" out, because he did not have enough cash to cover the short margins. If he did, the next day he would have been made whole again by getting way closer back to his entry point, when the market retraced back almost the whole way.
What I don't get is why you would call yourself a hedge fund if you are not ALWAYS hedged with something other than the shitty calendar-spread method? Did he have any options in there to do the offsets? It seems not. I figure that is what a hedge fund is supposed to do.
I really know nothing about options, but one thing I keep seeing over and over is to never ever "sell naked options." That isn't a hedge fund, that is just a one-way discretionary fund. In fact, my broker won't let you do it in your options account unless you donate a leg and sign away all your future children to their custody.
(Well, not really, but they take it seriously, heh.)