There is absolutely nothing wrong with the teaching that Jesus is the mediator of the new covenant for the anointed 144,000 only.
Sure there is Rattigan, and it is huge. If Christians are supposed to personally reject the new covenant "for forgiveness of sins" Jesus offered in Mt, 26: 27-28, then there must be some other NT scripture that shows how a person can get their sins forgiven OUTSIDE OF THE NEW COVENANT.. You cannot produce such a new testament scripture can you? No, you cannot. It doesn't exist.
Romans 5: 1&9 says that because we are justified we have peace with God. And, because we are justified we will escape God's wrath.
You cannot change this scripture no matter how much you may want to. It is there. Anyone can read it, understand it, and decide if they want peace with God or not.
Yet, your church (Watchtower) says people can no longer be justified. They say to just trust them to attain peace with God and avoid his wrath. This is anti-Christ Rebellion full stop.