You refer to opponents of abortion on the Supreme court, which points up a serious misunderstanding on your part. If its a vote of 9 elites testing their opposition or support, the court has lost all semblance of legitimacy. Of course that is precisely what Roe was, and indeed the court's reputation took a serious hit. The finest minds of the left have not found a valid Constitutional argument to support this decision in the intervening 35 years. The legal question concerns whether a generalized right to privacy exists whose borders are infinitely malleable based on the evolving whims of 9 members of a social elite. If this is true, then the people have no legislative rights whatsover, since every law can be construed as impacting someone's privacy. Your thought experiment takes us into the realm of public debate of morality, which is precisely what Roe has made moot. Still, to play along, those who view abortion as wrong almost always do so on supernatural grounds, not socio-politcal or scientific ones. As such they would not change their views to save the world in this fanciful hypothetical, since in their view God, not man, is the measure of all things. Indeed, why should they bother, since it and the rest of the universe end with an entropic whimper in a few scant billion years.