Makes the most since.
Russia would never admit to specific COMINT. They’ve not done this over decades of plying their craft, and it has served them very well.
This was a bunch of kids hacking, or an inside job, like ClimateGate.
Most likely, Guccifer 2.0 is what he says he is, namely a Moldovan hacker who is very proud of himself for penetrating the DNC's computer network so successfully. Read his FAQ (discussed on Hacker News). He's been dribbling his stuff out on his blog and his twitter feed for a while now. Stay safe, Guccifer!
Of course, it's possible he is a Russian creation. But if a Russian TLA did the job, I think it more likely they would keep it to themselves for blackmail use if she wins. Or fake an inside job, in order to sew maximum discord within the DNC.