So let's ask again: was Ozymandias right? No, because he was answering the wrong question. His craving for superheroism and his outlook on society pretty much confined him to commit genocide.
I would say not his "craving for superheroism," but more his craving for murder, because, man, does he love to murder! The method of death (The Veidt Method, if you will) doesn't seem to matter, although he does have a thing for poison. Whatever means are available to facilitate the ends, I suppose.
If the story went further I would expect Ozymandias to become more and more monstrous to protect his legacy. What's a few murders here and there for that after you have committed the ultimate crime? His saddened look after Dr. Manhattan tells him nothing ever ends might be his realization of there is no stopping there and what must he become.
We might disagree about the nature of his legacy. I'm assuming when you say legacy, you mean his tenuous and questionable acquisition of world peace; when I think of Adrian's legacy, I picture a new world modeled in his image. I think his ultimate goal was to conquer and rule the world. As evidence of this, look no further than the two people Adrian modeled himself after: Ramesses II and Alexander the Great, both conquerors and rulers of the world (or the the world as it was known to them).
Either way, to strengthen and keep his new hold on the world (or to keep the U.S. and the Soviet Union from blowing the world away), there's no doubt that Veidt would have no problem murdering millions more, all in the name of his new Age of Enlightenment, of course.