Longs and shorts are equally going down, i guess the cost of opening them is becoming cheaper too.
If this manipulator trusts stamp enough to let that many coins maybe he left there also the fiat from the constant dumping since August.
With most of leveraging out of the way he can now trust in the success of a strong self made upward impulse with the fiat he have on stamp. This would be a smart move by itself, but he could also exploit the low interest rate for going long on leverage.

could work?