Ryujin
Legend
And it is something that happens in real life as well.
HOWEVER, in most cases the HERO does not start off by placing the would-be sacrifices into harms way as the necessary prerequisite of achieving his goal- the trope is presented as a choice between bad options that he must make the call on. Nor does the Hero conceal his role in the sacrifice. Nor does he blame another for his action. Nor might the plan be jeopardized if the Hero's true role and actions were to be uncovered.
The Hero usually doesn't find it necessary to trick semi-divine, semi-benevolent, nearly omniscient beings into not interfering with his plan.
The plan is Machiavellian- not heroic- in its inception and execution. He wanted to do it his way. Only.
I would say that the requirement that- for the plan to succeed- you must commit an atrocity AND successfully blame it on the blameless makes for an inherently flawed plan. If the truth is ever revealed, it could make the duped discard the progress made, and return to previously belligerence. Possibly even more pissed off than before.
Have you read much Batman over the years? He leans pretty hard on the Machiavellian side and is still considered a hero. The difference is in scope. In this case I would liken the decision to having a nuclear missile full of children hurtling toward a national capital, with its destruction being the only viable solution to the problem. But that's where our opinions diverge. I think that the character had a high enough level of intelligence to recognize an inevitable conclusion. You don't think it was inevitable.
The point if the story is that Ozymandias fails, or at least we can presume that he did, as a result of his plan being revealed by a hero who is either less "morally flexible" or can't see and act upon a larger picture, depending upon your point of view. Perhaps a little from column "A" and a little from column "B"? Maybe that's the point?