I'm not saying that the inclusion of 'Nimoy-Spock' was a bad thing...
It really made no sense at all.
Actually, it does. Notice how as soon as NuSpock asks "how" the original crew beat Khan, they cut scene. If I had to guess, Spock probably said something along the lines of "we hoodwinked him," which is exactly what NuSpock proceeded to do. Spock Prime probably gave him the inspiration for what they did with the torpedoes.