Considering the USA is basically a fundamentalist ('turn the other cheek') Christian country, that's the first time since 2001 I have heard someone offer forgiveness to Osama. If the Lord didn't mean for there to be terrorists, he wouldn't have given you Guantanamo Bay.
Military systems should be better protected, McKinnon didn't have to try very hard by the sound of things. If I leave my kitchen window open, and you walk past and steal my teapot, you should be done for theft. If I then call in a team of security consultants to tell me how to close my kitchen window, and they charge me £10,000, that does not mean you should be tried for commiting £10,000 worth of damage, it just means you are a thief and I am a dick.
Imagine the people in charge of that network reporting the hack to their bosses, they have two choices.
1. Admit that they are pathetically bad at their jobs.
2. Make out that the person who took advantage of their lack of ability is a criminal mastermind.
McKinnon's activities don't seem to have caused any person any physical harm. So the problem must be all about the money it cost to put right his meddling (or more accurately, the money it cost to put the security measures in place that should have been there from the start and prevent any future embarassments).
If it is about the costs, then yes I would say spamming is worse than military hacking. Spam cost the whole world much more money than McKinnon's 'military hacking'. Estimates range between $20 and $50 BILLION a year. Most spam comes from the USA:
McKinnon is a meddler (maybe a malevolent meddler, yes) - he needs to have his wrists slapped. He doesn't need to disappear into Gitmo and be tortured by rednecks.
Extradition generally isn't overkill. The idea of extradition to the present day United States of America for a crime that they can interpret as a kind of terrorism, is terrifying.