Jonathan sacks o.b.m., was not a posek. He was a theologian rabbi speaker person. His statements do not establish anything except his own opinions. They definitely do not determine what is a living thing and what is not
As has been noted, there is a degree of question among achronim as to the status of an uber/fetus. That being said, in practical halacha, the great tzitz eliezer should not be counted together with rav moshe. They were simply in different universes. A psak from the tzitz eliezer when compared to the ineffably vast torah depth and bredth of רשכבה”ג maran rav moshe, is not counted.