He does not deny his actions, but that's not the same thing. It is yet to be proven that a crime has even been committed. Even if that can be established, the gravity of the crime will still be a matter of dispute.
That's a false analogy. Your house is your privately-owned house. NASA belongs to the public. So we are not talking about unauthorised snooping of information on a privately owned system - but on a publicly owned system.
If the public owns systems on which information is kept which is to the benefit of the public - this is McKinnon's claim - then, arguably, the public should know about it.
To draw an analogy: it's not a crime when an overseas non-Chinese citizen makes a temporary dent in the Great Firewall of China, allowing Chinese locals to briefly use search engines to look up how the Beijing authorities responded to Tianenmen Square demonstrations in 1989, is it? But of course, this is information that the Beijing administration would not like to be widely available, so they will certainly call such hacking "a crime".
Do actions constitute misdeeds or crimes whenever the administration (be it the government of a de-facto one party state or a de-facto two party state) say they do?
Probably one for the courts to decide.