No matter how you look at it, he is a traitor. He violated the UCMJ. Although he is free to make ethical arguments as to why he leaked Collateral Murder and the US Embassy cables, the US is fully within its rights to prosecute him.
I’m quite consistent about this: Treason is a punishable offense, no matter where and why it happens. I do not have an issue with the US executing the Rosenbergs or the USSR executing Western spies during the Cold War either. It’s part of the risk you take when you choose to sell out your country for a few shekels. This likewise applies when you do it not for money but for “idealistic” reasons.
I agree that in a perfect world, the fact of Manning (1) releasing it out of ethical, not monetary convictions and (2) giving the entire world access to it, as opposed to foreign hostile intelligence services – unlike, for instance, the Russian KGB traitor, Vasily Mitrokhin – should be a mitigating factor. However, as a sovereign nation, the US has no obligation to take that or international left/liberal opinion into account.
The Assange case is completely different. Here the US is trying to extend its jurisdiction to the entire world, so that an Australian citizen can now be found guilty of “espionage” against the US even if he’d never stepped foot inside it. This is called imperialism, and we are opposed to it. What’s more, the methods used to do it are particularly nauseating and underhanded. The probable plan is to extradite Assange to Sweden, from whence he can be quietly renditioned to the US. All based on incredible and patently false rape accusations, questioning which is going to get you blacklisted and smeared by legions of Guardianistas, PC brigades, concern trolls, and sundry useful idiots of imperialism. It would be infinitely more respectable for the US to just whack him.
That is why I support Assange to the hilt, but don’t care for Manning. It’s a very logical and consistent position, I think, but many don’t see it that way. They view it as anti-American, misogynist, and reactionary. I think it is pro-American, anti-imperialist, and pro-rule of law.