Don't know how separated the German judiciary is from its government, which seems contradictory on its position, but for Snowden to accept some sort of German judicial protection would be on hell of a gamble. Could be a great solution, but could also result in a one way ticket to the US. At least Germany has a reasonable and comparatively open political and legal system, which doesn't rely on politics and cash in the bank.
On the face of it, if the Germans did go this way, in the way suggested, I think I'd take it. But Im willing to bet nothing is quite that simple, or likely.