Whether or not the outcome is "good" or not in a given situation, a true Machiavellian attitude is close to how a sociopath thinks.
Ok. But being a sociopath doesn't make him wrong, even if he is one.
Sociopaths ignore what is right/wrong (if they subscribe to a traditional moral code to begin with)
But I don't think Veidt does, and that's what's relevant. He would rather not
do these things, but he does in order to ensure the security of his plan to prevent an even greater disaster.
or at least bend the rules of morality in their own mind to accommodate their situation.
"Rules of morality"? Even assuming there are such rules, Veidt puts forth a simple idea: an act which, independently, would be considered to have a negative impact on society, if committed to prevent a greater negative impact, is moral, so long as it is more reliable than any other available solution.
Good becomes bad and bad becomes good dependent upon what they desire, and decisions are made based upon a self-justification to their warped codes of conduct and/or morality, which only really exist to further reinforce their own deviant behavior.
Veidt follows a simple, ethical, logical code. The only deviant behavior he's guilty of is saving the world and then working to make it a better place after he accomplishes that. Everything else was a means to that end; an unfortunate consequence. He avoids killing, and he barely even has any vices except a substantial ego - even his absurd fortune was merely accumulated so that he could afford his plan.
Compare him to someone like Nite Owl, who beats up someone in a bar just because they give him bad news. Rorschach, who barhops, beating up lowlifes, even if they've done nothing wrong - hospitalizing many of them - not to mention his rampant right-wing biases and prejudices. Blake, a sadistic war criminal. All three of them take pleasure in violence at points. Rorschach even calls it his "exercise." Veidt? The closest he comes to that is when he kills Blake, and even then it's because Blake tried to tell someone about his plan, not because he wanted to.