I can on his behalf, because I understand where he's coming from (though I don't agree with the conclusion). I've actually heard this argument a number of times before. Obviously I'm not speaking for him, just my interpretation of where he's coming from.

Snowden revealed the things the NSA was doing that he believed to be illegal. The government agreed that what the NSA was doing was illegal, but no one really knew about it before Snowden revealed it. However in the aftermath, the government decided that while the NSA was doing something illegal, they were doing it because they believed it was necessary, and the government agreed. So they changed the laws to make legal what the NSA had previously been doing illegally. The net result is, everything Snowden warned us about is now legal and nothing has changed.

An unfortunate, unintended consequence, but I would strongly hesitate to blame it on Snowden. If he hadn't said anything, it would have continued, hidden away. If he did say something, it would be codified into law. Net result is, it was going to happen anyway. But at least everyone knows about it now, and I consider that to be a positive.