My personal take is that the guy is likely telling the truth that he was just looking for proof of extra-terestrial life, though as others have said, this doesn't really excuse him from hacking the most paranoid government in the world and expecting them not to take action.
However
I personally think that the Americans are trying to make an example of this man and Aspergers or not I don't find this acceptable. I agree this man should be held to account but not in the way that is currently happening.
Oh, and just to clarify, when I said it sounds plausible, I meant it in regards to the Aspergers diagnosis which I did not make very clear in my opening post.
In my opinion the man involved would be much better put to use working for the government, preferably here in the UK, then by the overblown actions America is currently pursuing against him. That possibly means some jail-time first as nobody living in a society should expect to break rules and not face consequences.
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The more I learn, the more I realise, the less I know!