It's not reckless, it's business. They are just dumping their personal coins before they announce something that makes the price drop more.
Why do you need their announcement to realize the situation?
Like the MtGox folks, who believed that everything was ok as long as Karpeles didn't say that it's all gone
I'm pretty sure they dumped their coins ages ago.
I'm pretty sure that if they would have dumped all of their coins, then the price would stay at 10$ or less.
FBI seized 250k of DPR coins that he earned with commission. And these were the coins that were given to them, without knowing if DPR actually has more coins. If you understand the technical properties of bitcoin, then you know how easy would it be to hide your funds, with only you having access to them.
Now imagine the amount of business that goes on at the exchanges. Think about commission that they are earning and think about how little expenses are needed to keep an exchange running.