That's because even if you did follow the NSA, you assumed they spied on foreign government officials, "bad guys," not _everyone_. That's the source of the surprise. I don't know anyone who's surprised that the NSA spies on, or hacks into foreign government agencies.
Another thing is the wording - Andreessen says Snowden's a traitor by the basic definition, in which he stole national secrets and gave them to our enemies. That is a consequence of his disclosures. But this information was hidden from the American taxpayer (which is also easy to justify because we all don't have security clearances), but more egregiously, the information was hidden from Congressional Committees that actually have direct OVERSIGHT. And they have security clearances, so what's your excuse then?
So sure, the Russians and Chinese governments now know what the NSA is up to. But that was their full time job to find out and they are probably hardly surprised.
But thankfully, even Congress and the American public know exactly where our taxes are going. And we really aren't the enemy of the NSA.
What we ask our representatives to do with this information will say it all.