Those transfers with private keys are unrelated, I explained it in different comment here.
When it comes to power down (a.k.a. unstaking) it's full powerdown, i.e.
29526702 SP on steemit account
That's over $6.1M with current prices, 1/4 every week.
What they are up to?
Hard to say..
paying debts, court orders, or maybe just (ab)using recently acquired company assets (those who were supposed to be dev fund) to use for shilling like it seemed to happen before:
Those are just guessed based on past events, but maybe I'm overestimating and it's going to be just usual pump & dump.