Why does the world/humanity require an authority on security? What principled ruleset will be enforced and not corrupted by those humans running it, e.g., see the behavior of these freedom and democracy loving societies/countries post WWII... stability for some.
You are for American imperialism as you see it as a global and local good. There are nice tales about morals and ethics that make you feel good about yourself and your position in local society and the broader world. That is all well and good, but others exist in the world and they have experiences, cultures and opinions too. Which is superior, who decides and by what ruleset.
I don't think that American or any other grouping having supremacy is a good thing. Of course, this is the real problem right now, the old post WWII order is slowly decaying as the world reverts to some form of mean. The winners of said war are as happy about this as the others were about being told how to live and behave. Such as it always was in a way.