chapter 4
It was a temporary solution. Manhatton and Rorschach both knew this, but Rorschach would rather let the world die instead of delaying it with a lie.
I think it is more that Kovacs gotten beaten up as 'the bad-ass' Rorschach and completely shamed by Veidt... so his big moral high-ground stance is more because his ego got hurt real bad AND the 'bad guy' actually saved the world (even though it might be temporary).
A very interesting interpretation but one I certainly didn't draw from it.
Rorschach was completely unwavering in his search for the truth and I like to think nothing could deter him for unveiling it not even world peace.