The UN and “international law” are not the final authority on anything. International law is a loose collection of treaties, trade agreements, conflicts, supply lines, and pinky promises. It only takes effect in a democratic nation if the people vote in a government which makes it a law.

The UN is a political organisation, not a neutral arbiter. During the Rwandan genocide, the genocidal government still held a seat on the Security Council while the UN reduced its peacekeeping force. Iran was elected to the Commission on the Status of Women. Libya and Russia were elected to the Human Rights Council. These appointments are driven by bloc voting, diplomatic deals and state interests.

International courts are not above politics or error. Their judges are selected through a system in which dictatorships and abusive states have a vote. The UN is not a democracy. While each member state might appear to have one vote, that does not indicate their power, influence, credibility, or moral standing.

Note how I did not make a judgement on whether Gaza is a genocide. I am merely explaining that deferring to the dictatorships and pinky promises is not a good argument.