Moral objectivism is an ethical position that states that the system of ethics should be the same for everyone and people cannot have a different set of ethics applying to them just because they are different in some way, which could include race, sex, religion, etc.
A system of ethics that is not universal is bound to allow some people to justify the actions that they perform and also assert that if others do the same it is unethical.
This is a stand that a person may attempt to take in the name of moral diversity. As an example it is ethical for a man to beat up his wife is she refuses to sacrifice her career which pays her more than her husband is earning because the husband wants to have a child; but the wife cannot demand that her husband give up his job and look after their 3 year old son.
The universal righteousness of moral objectivism is something that has now been well understood and almost all universal policies and agreements take this into account.