Why wouldn’t you take their rhetoric at face value. I know a lot of them. They genuinely believe what they say. I think you need to separate the politicians from the voters. All politicians are lying hypocrites.

Abortion isn’t illegal and under threat because those people sincerely believe anything. They have very little power, like us. The people who have the power to make it illegal are those lying hypocrites you’re talking about.

If it weren’t a material political issue, I’d probably be interested in the question of whether a fetus counts as a person, if abortion is murder, and that kind of thing. But esoteric philosophical questions like that don’t actually have much relevance to the political conflict over abortion.

As for arbitrary. Nothing is inherently true outside of the physical sciences so all morality is arbitrary, it’s just based on the subjective preferences of an individual. I once heard a (secular) philosopher in an interview that morality is just like liking the smell of a flower. It’s entirely what you personally prefer even if that preference is subconscious.

I think this view misses a crucial feature of the human experience, which is that we necessarily live from a subjective POV. If you want to take a universal perspective, untethered to any constants and separate from human cognition, then yes morality is as subjective as you say. But by choosing that frame of reference you’ve ensured that none of your conclusions are relevant to humans. In order to say anything worth saying by humans, you have to accept a subjectively human frame of reference. There’s not a lot of utility, for humans, in any other frame of reference.

People don’t think murder is wrong because they prefer to live in the same way they prefer vanilla over chocolate. I don’t think anyone actually understands morality in that way. People can disagree about it and there may even be no definitively correct answer, but when someone says “that is wrong” they do mean something different from “I dislike that.”