Senator McCain is almost certainly referring to compartmentalized intelligence [1].
So he's not saying the spying was egregious, but instead that allowing a contractor like Snowden to have access to the classified info about the spying was egregious.
To be fair, you compartmentalize intelligence so it does not get abused. If you don't have a <need to know>, it is presumed you are going to abuse it somehow. That's the purpose of 'need to know' restrictions. Yes, it also is a policy which increases OpSec. But note His interview reference seems to be wikileaks and Manning, which was a breech of opsec, in theatre. Snowden leaking on the NSA seems to be much more grounded in a principled position, and is in a civillian context. Its hard to infer a position on the latter based upon coments from the former.
So he's not saying the spying was egregious, but instead that allowing a contractor like Snowden to have access to the classified info about the spying was egregious.
[1] http://en.wikipedia.org/wiki/Compartmentalization_(informati...