My understanding is that Manning reported that if she could crack an NTLM password she could better conceal who obtained and leaked the documents. A party, apparently Assange, claimed to have rainbow tables and could try. Later Manning followed up and got a no-luck-so-far response. I have not heard any reports that Assange actually did so.

So the facts are that Assange is accused of helping a leaker cover their tracks-- something that a journalist would ordinarily do, at least in so far as if it came to covering their traces against normal physical detection (e.g. refill the copy machine after copying a big stack of documents...). One could have an interesting debate on how equivalent cracking a service account to cover tracks would be to something like finding a department generic code to redirect copying billing attention ... but there doesn't even to be any evidence that he successfully provided that help.