Now I realize what was the reason for the mid-move turn back at 510 and the quite strong selling towards 400, which was not supported by fundamentals or anything.
The attackers have taken a short position during the decline (causing the decline), and when they run out of coins, the price also stopped declining. When it started going up, it was the time to attack.
Now if the holders sell their coins so that the price drops to below 400, without corresponding buyers except the attackers, then the attackers have won financially, fleecing the community. (The community has also won, because the bug was fixed and attack repelled.)
I pledge 1000 XMR to the devs for their ongoing good work, and BTC100 will be used to buy moneros in the exchange without further warning if I deem that the scamattackers are about to get too fat a profit from their attack.
Yeah... that's called an "exit pump".