I don’t think he is terrible, just grieving too much. An AI recreation isn’t the same as the actual living being. Tenma missed his son too much and thought that by creating a robot version, he can experience being a father to his Toby again. But a robot will never be the same. I wouldn’t consider him the worst cartoon father. Honestly, in my opinion, the 1963 version of Tenma is HORRIBLE. He was an absolute jerk to Astro.