More on Zero Requiem

Nietzsche said that all actions are fundamentally governed by what is fundamentally self-interest.

There is several distinct ideas in your text. Overall it is all over the place.

First is Scarcity of Resources. Scarcity of Resources indeed produces a conflict. People fight over who will get the stuff. All wars and even sports competition is ultimately about it.

Actually, it is Scarcity of Resources principle that invalidates all of the anti-war ideas of Code Geass. 

Second, there are fates worse than death. You might want to kill yourself to avoid any of these.

That however does not apply to Zero Requiem.

Zero Requiem was needed because world just could not accept what happened. 

Lelouch conquered and united the world into a single political structure by force. However that was mostly against the will of the people he united.

Thus, people of the world were just unwilling to accept something like that. People hated Lelouch for denying them and their countries their independence.

Much like people of Area 11 resisted Britannian rule imposed on them by force. The rest of the world would likely to resist Lelouch's rule imposed on them by force. 

Not the kind of result Lelouch wanted to see.

Thus a some sort of solution to this problem was needed. So he came up with Zero Requiem. Zero went out of nowhere, killed oppressive dictatorial Emperor and liberated the world. It is partly symbolic but also substantial in some regard.

Now world is not only united into a single entity but also liberated from oppression. They did not liked tyrannical rule of Lelouch. Zero saved them from it. 

Now united humanity is free to build their new free future in the world Lelouch left for them.

The fact than Zero killed Lelouch will eliminate all opposition to the new order from liberal perspective.

Since democratic institutions of UFN can fully function after Zero Requiem, people have no more reasons to think that world is run by a tyrannical authority against their will.

Even if they hated Lelouch and his new order, now, that he is dead for the public, they have no further reasons to start an insurgency similar to Black Knights to remove him form power.

Nunnally and the UFN are not hate-able at all so no one will want to start an insurgency against them.

World that content with what happened rather than world that resist his rule is the kind of world Lelouch wanted to make and see. Zero Requiem was needed to achieve it. An ultimate 3D chess move to get people where he wanted them to be.

Here is was done both for him and for the world.

And to top it up, he survived. Though it is an information to which few are privy. 

They of course did not announce it that he survived.

Officially and legally both Lelouch and Suzaku are dead after Zero Requiem. However you have seen where Suzaku really was.