The indictment cites Assange saying, "no luck so far" after asking some questions about the stuff Manning is sending him. You want to read complicity into a vague statement made to excuse non-contribution, whereas there could have been any number of reasons Assange replied that way, such as not alienating a source, or laziness, or knowledge that actually doing anything would put him in legal jeopardy.
There is no actual claim here that Assange did anything to crack the system or assisted Manning in doing so. He is not accused of delivering a password. He is not accused of downloading password cracking software. He is not accused of contacting others to ask for their assistance. He is just accused of saying, "nope, can't help".
If there is evidence that Assange delivered cracked passwords to Manning, I'm sure that people will change their minds and agree with you. But that is not what the indictment claims. And the lack of anything more specific in such a high-profile case suggests there is nothing more that they have on him than an ambiguous statement of sympathy with a source.