According to this, could one have made a legal argument in the famous Roe v. Wade case in the United States that even assuming the Constitution did not regard a fetus as a person, or that a law against abortion infringes on the mother’s freedom of action in a way that contradicts the Constitution, still natural law takes legal precedence over the Constitution and therefore the act of abortion itself is legally forbidden?

First, the problem is that here too you are again entering the legal arena. If the court had decided this without arguments from the sides, that might have been similar.
Second, even in the meta-legal arena there is a significant difference between the cases. In the case of the Nazis, we have a claim against every person there that he should have understood on his own that this was something that simply must not be done, even if the law required him to do it. That is obvious to every reasonable person. Therefore we expected him to resist and refuse to take part in the acts of the Nazi regime. That is why he can be punished without a specific legal justification, because he bears guilt. But on the issue of abortion, whatever your opinion may be (and mine), it is clear that a considerable part of the public sincerely believes that it is legitimate. Here it is hard to say that the woman should have understood that this was something that must not be done, when most reasonable people do not see it that way. She bears no guilt as long as the law does not forbid it.
The boundary is of course a fine one, because there could be a situation in which a person does something that is considered by his surroundings to be a severe moral offense, but he sincerely believes it is permitted. I assume that in the early days of abortion this was still the situation. So there, I suppose, many would compare it to the Nazis, because in their eyes it was obvious and there was full social agreement about it.
But in Roe v. Wade, which was heard in 1973, that was no longer the case. On the contrary, there the Supreme Court had already ruled that such a law was unconstitutional. That is, there was already broad social agreement around the legitimacy of this act.
You’ve raised an interesting point, which connects for me to a post I’m writing right now. We’ll see what I do with it…

Regarding abortion,
those who permit abortion could argue that even if natural law or morality forbids it, the positive-law right to life of the state does not include fetuses.
Regarding the Nazis,
the Rabbi’s argument can be formulated in terms of a religious court may administer lashes and punish not according to the formal law, for the sake of repairing society.