Well, even if it wasn't Russia that hacked the DNC (and now the Clinton campaign) it is still the case that someone did, and that's still reason enough to take the measures Bruce Schneier's advocates.
Also, there's been some claims that NSA and other agencies are running TOR exit nodes. Not sure if there's anything to it, but the point is state level actors have resources that nobody else does.
Besides, I am not sure what is your point. "Russian hackers would have covered their tracks, therefore it must not have been Russian hackers"?