i think its a miner/mining company that has been mining a monster rig and only sold enough coins to cover costs, and because he knows if he waits 3-6 months the coins hes already mined are worth more than when he mined them, (something like, sell from nov - jan, hold from jan - next bull run) and therefor makes more profit on his profit. perhaps now he is simply selling coins he mined after the price fell bellow 600? - and now will the money to develop/buy new mining gear to stay ahead of the other miners. not too outlandish is it?
Plausible. Not likely due to the timing. But reasonable.