If an act is morally wrong then the actor lacks sufficient moral reason (and arguably sufficient non-moral reason either) to so act. But can it really be a 'relative' matter what (moral) reasons Sally has for acting? Surely the relevant standpoint here is Sally's own. She has (moral) reason to act as her idealized self would (morally) recommend, and - ex hypothesi - her idealized self recommends abortion. So Sally has sufficient reason to get an abortion. So it cannot be morally wrong for her to do this.
At what step can Anne disagree? Anne's idealized self opposes abortion, but that is merely a reason for Anne to not get an abortion; it is not a reason that is relevant to Sally's action. Anne can see that Sally is perfectly justified in her beliefs and actions. So she can't maintain the claim that Sally's act was wrong; all Anne can claim is that it would be wrong for her to perform a similar act of that type. Sally, seeing Anne's standpoint, will agree: it would be wrong for Anne to get an abortion. But now there is no disagreement over token actions. So the moral truth isn't 'relative' after all: it's absolutely true that Sally may get an abortion and that Anne may not.
You might dispute my assumption that what practical reasons S has is a non-relative matter, determined by S's standpoint and no other. But even if you dispute that, so that Anne may (as yet) hold Sally's actions to be unjustified, Anne presumably cannot deny that Sally has rational beliefs (insofar as they would survive idealization). But now we can appeal to Clayton's principle for moving from Theoretical to Practical Reason:
(1) If a subject judges that she should Φ and it’s not the case that she should refrain from judging that she should Φ, it’s not the case that the subject shouldn’t Φ.
Anne must grant Sally the antecedent -- Sally judges that she should have an abortion, and makes no mistake in doing so -- so Anne must also grant the practical consequent, that Sally didn't act wrongly.
We thus find that moral relativism is incoherent. On the assumption that relativism is true and applies to some token act, it turns out that it doesn't apply to that token act after all. Contra the assumption, moral status is perfectly 'absolute': if the agent commits no (theoretical) error in thinking their action permissible, then it's permissible. Since the former is a non-relative matter of fact, so must be the entailed consequent.