1.Logic.I could not complain about being robbed,when i steal myself.Wtf is even "right to complain"? Who grants or takes it away, by what standard, and by what power? You are trying very hard to extrapolate legal principles meant to work on the scale of a single polity's sovereignty and legal system onto the global state, where everyone is sovereign unto themselves and has their own legal system, or more than one if they want to.
Unfortunately everyone else doesn't share this preference. Other civilizations don't give a shit really. The weaker ones will demand your "justice for everybody" when it favors them until they become stronger, because that is your principle, while the stronger ones will do what they want, because that is their principle.
Universalism has failed, the lesson of what the western civilization got for trying is that gentlemanly agreements are nice, but they need to remain just that. Agreements, not unconditional and universal laws. When the other side doesn't follow an agreement, we shouldn't consider ourselves bound by it either, otherwise its just a self imposed handicap, which is not something a sane civilization does.
And if we create enough of these handicaps for ourselves, then one thing is certain, we will never again be faced with philosophizing about the question of whether justice should be for the strongest or for everybody, because certainly someone else will be the strongest, and as such, they will answer this question for themselves, without care about what the western civilization thinks of it.
2.You missed a point.I do not say about being nice to thugs,but about using the same morality for everybody.Which include killing murderers or thieves,becouse i would do the same to my people who would do so.