Well, you could make the same argument in court. Why allow defence to present their side of story? What if they lie and spread misinformation. Better not listen

Well, you could make the same argument in court. Why allow defence to present their side of story? What if they lie and spread misinformation. Better not listen to them and just make a judgement without them. By not allowing Russia to present their story because “what if” you are preemptively saying that they are guilty. Why was Ukraine allowed to participate?