Because not even they take a truly pro-life position. Like the rest of their colleagues they have never stated a word of support for Fourteenth Amendment equal protection for the child in the womb.
That's right. There isn't a single sitting member of the Supreme Court who is pro-life. Not one.
-- Justice Harry A. Blackmun, Roe vs. Wade majority opinion, 1973"The appellee and certain amici argue that the fetus is a 'person' within the language and meaning of the Fourteenth Amendment...If this suggestion of personhood is established, the appellant's case, of course, collapses, for the fetus' right to life would then be guaranteed specifically by the Amendment."
Semantics. But no point in arguing, fundamentally I agree with you on this point.