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
https://steemd.com/tx/ef2d2020fadae5dfc7af8449f0fe5f8262e20e42
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.
https://markets.businessinsider.com/currencies/news/warren-buffett-lunch-tron-justin-sun-spat-bram-cohen-bittorrent-2019-7-1028388483
https://cryptonews.com/news/justin-sun-admits-his-lunch-with-buffett-is-not-sponsored-by-4022.htm