How do you know? You're one of them?
Just because they said being white hat hackers doesn't mean it has to be true.Maybe just some tactics to prevent another fork? I mean $110 million loss is something.
And even if that should be the case and they are "white", remember what happened last time at the DAO? The white hacker tried to sell parts of the "saved" coins on Poloniex!!
So far nobody knows what's going to happen!
Ethererum, Solidity and all its with it connected Software is just a paradise for hackers.
Has much more holes then swiss cheese!