Even if Snowden gets this assurance from the Norweigans, how can he be sure they're not lying? E.g. the US tells Norway they should say "yeah sure we won't arrest and extradite you," then go back on their word and arrest him as soon as he enters the country. The US makes some under-the-table bribes or threats to be sure Norway goes along with this scheme. Something along the lines of "It sure would be a shame if we t…
And come on, snatch and grab inside a sovereign state, that is a close ally and with all the media attention his has. You don't really need to be an intelligence service to notice a guy like Snowden suddenly disappearing.
Ask Israel how much we like it when foreign states interfere within our borders. They are still more or less out in the cold after they executed the wrong guy. A Norwegian citizen, within Norwegian borders. You just don't do that.