To me it seems like someone trying to stimulate others to buy. (when i used to have 1000's of usd sitting i'd just play dark bids). Might be someone who wants to dump a larger sum.
There are no dark orders anymore. But, you may still be right: sellers always reacted slowly so far, it might be profitable to do a "scare" order to sell at higher prices and pull it when prices close in.
However, we have very little volume, so I somewhat doubt it. It would make more sense for a daytrader, who estimated price above his bid anyways and wants to make profit in an upwards spike with his remaining coins. Yet, more likely, it's someone who sold at a higher price and would buy back in if it drops. (Price estimator kind of person)
The really important question IMO is whether the funds were newly added or come from Bitcoin sales. If they come from old sales, they will run out at some time and cease to play an important role; if they were newly added, more might come the same way.
