Are you saying you think he did know about Stratfor and likely would have hacked it anyway?
There is an IRC log somewhere of lulzsec talking about Stratfor, only one person knew who it was. It has to be characterized in very simple terms for the others (about 8 people there) to get what it was. They all wanted to continue scanning .gov and had to be convinced of Stratfor as being value.
I am almost certain the Stratfor idea came from outside of the group. Hammond was the most politically involved and savvy yet he didn't know about them, I really doubt Sabu did.
The other part of this is that the Stratfor hack has been represented as the work of one man who only got a little help along the way, when it was a few individuals involved. What distorts this case is that the only source of information is Sabu. Since Hammond trusted Sabu and spoke to him a lot (although I think Hammond knew that Sabu was more operations/motivation than skill). So naturally there is more evidence against Hammond, than there is evidence against Topiary and the europeans who spoke to Sabu much less and didn't trust him.
The Sabu evidence gave the feds enough information to issue Hammond an entirely separate indictment for Stratfor, something that happen nowhere else in Lulzsec hacking cases.
He has been charged with nothing else. All else that the case established was that he had views sympathetic with parts of Anonymous and he hung out on their IRC channel a lot. Charged with credit card fraud and $1M in theft even though the guy was eating out of a dumpster.
I think it would have been fair to imprison him for 18-24 months like a few of the others, he seems reformed in any case.