No State shall...deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
Even Blackmun, in the written Roe vs. Wade majority opinion, openly admitted that "if the fetus is a person," they are "of course" protected by the Fourteenth Amendment.
So, he and his colleagues dehumanized the child.
But we have pro-choice for states Republicans running around admitting that the fetus is a person, as it clearly is by any modern scientific measure, and yet are still saying that the states can allow them to be killed if they want.
I say the latter position is worse than Blackmun's.
As to the Fourteenth, I suspect some of the folks you're talking about would be making the sort of distinction that came up in Shelley v. Kraemer - that the 14th Amendment only forbids "state action" and that most abortions are private events and not the act of the state government. I think even those folks might agree that the 14th Amendment would prohibit a state from imposing an abortion contrary to the mother's wishes.
In any event, I suspect the the folks you're talking about are making that kind of distinction and thus feel that a state can properly refuse to make private abortions illegal. Does the 14th Amendment require states to criminalize all forms of homicide?
I see your point and I think the Shelley case provides some ammunition for your position, but I can imagine a Supreme Court going the other way.
A related question is whether the Federal Government would have the power to pass a law banning all abortions nationwide. I think that it does have that power, but I recognize that there are some states rights fans who would disagree with me on that.