You know, the logic in this story is very twisted. Naruto wants peace and justice but the only thing he's doing is rampaging revenge on all the 'villains' that seem to have a slightly different perspective. Nagato wants peace and justice and the way he's going to do that is by blowing up villages and collecting the 9 most dangerous beasts manifested from hatred and evil. I wonder if this whole thing will end a little more diplomatically with the revelation that there is no peace, I mean, that's why ninja's exist in the first place, isn't it?
Nagato's definition of Peace is incredibly simplistic. He sounds like he views peace simply as the absence of war. If that's your starting point is that then Peace through oppression is still peace. It's closer to enslavement than genuine peace. Pain will fire the weapon and fear of it's further use will prevent anyone from doing anything that encourages its further use, in this case war or things considered acts as war. If you see peace as being the equivalent of no war then you get what you want even if its through mass murder and brutal oppression. He also seems assume his own death in all this and that his demise will cause people to eventually forget, at which time war returns and someone else like-minded takes his place and Peace resumes.
I don't think Naruto's ideas of peace are what drives him to defeat Nagato. Despite what Naruto says here, Naruto always appeared to fight for the protection and preservation of what he holds dear and, aside from his way of the ninja, Naruto appears to value his precious people more than ideals like Peace or Justice.
One thing I wondered when he swore vengeance for Jiriaya's death was how Kishi could distinguish this goal from Sasuke's pursuit of Itachi. Kishimoto essentially side-stepped the problem by having Naruto meet Pain now because Naruto can fight Pain as a matter of protecting what remains of the village and its people. He can obtain his revenge in a fight of protection, meaning Naruto never has to independently justify his pursuit of vengeance. It's disappointing in one respect because I would have loved to watch Naruto try and explain to Sasuke why his relentless pursuit of revenge is wrong and why he should return to Konoha.
By going after the same thing Naruto, would have obliterated any moral authority and would have sounded like a flaming hypocrite by saying that. It would have been a great scene, but the timing of Pain's assault and Naruto's return makes that irrelevant by giving Naruto and independent reason to pursue Pain specifically.