No doubt what state depoartment wanted.
So a Guardian journo publishes the key to an encrypted file.. thinking it can somehow 'expire', or that that file is super-secure and will never find it's way out of the hands of a select few. Probably done mostly for 'see what we know! na-na-naaa! willy-waving reasons, but maybe requested by someone? If you want to blame Assange then at least do it for the act of providing the leaks to journos in the first place; he is not directly responsible for publishing the password.
Also; for this to be 'devastating' the file needs to come out too; and how did that happen? it miraculously pops up on the Entertainment Industries favourite whipping boy, bittorrent! humm. lots of idiots and dark actors about.
It's quite possible that the Hillary, or rather the manipulative thugs in real power, wanted this out. It will undoubtedly be used to try and convince the grand jury that the argument the leaks were redacted is false, and that somehow Assange is culpable for this leak too. Maybe they can get that indictment they so crave.
The spooks wont really care for all the little people who will suffer; stopping this dangerous idea that free speech applies to us all, and not just the powerful, is far more important. And in the meantime they get one step closer to extraditing their nemesis; and garner a vast amount of righteous indignation from the mouthpieces of Fox etc.. These are people who think they are chessmasters; losing a few pawns is no matter.