Actually, my experience for the last few years is that fewer and fewer of the pro-aborts try to defend this prof's scientifically indefensible position.
That the embryo/fetus is a human life is quite simply a scientific fact.
What I see more frequently today is grudging recognition of that fact, accompanies by one of two rationales for nevertheless allowing abortion.
1. The embryo/fetus is not "a person" under the terms of the US Constitution, and so is not worthy of the protection of its civil rights. The original Roe decision is actually quite good at supporting this position. It is highly unlikely the original Founders or those who ratified 14A had any notion they were talking about preborn children.
2. Yes, the preborn child is a human life, but it is a parasitical invader life, and is not as important as the life of the "mother," so her preferences/convenience should take complete precedence.
I'm not saying I agree with these positions, simply that these are the ones I've been seeing more often recently.
Just to weigh in, not to argue with you of course:
1. One should ask a person who supports argument 1, “Did the authors of the 14th Amendment envision anchor babies?” When of course they answer “no” their argument is destroyed. Or ask, “Did the founders envision the Internet vis a vis the first Amendment?” When they answer no their argument is destroyed (because by such perverse limiting logic, the first Amendment protection can’t apply to the Internet, since the Internet wasn’t envisioned by the founders.)
Finally it’s sickeningly ironic such an argument would be used in the first place in defense of Nationalized Abortion. As the entire argument for forcing states to permit it rest not on anything specific in the Constitution but on the “penumbra” thereof, which is, by definition, “not envisioned by the founders”. Hypocrisy heal thyself!
2. This is a common misapplication of the “invader” argument which can take many forms. Basically it says an invader of personal space has no right to said space uninvited.
Certainly true enough but it ignores one key fact: the baby inside the womb didn’t “choose” to “invade” the woman. It’s a subtle but significant difference that differentiates it from a mere parasite.
A better analogy (and one that destroys #2) is to compare the baby in the womb to, ironically, another baby but one outside the womb, left on one’s doorstep by a poor mother. (Note this can be done since the one making the argument in #2 has already conceded the “thing” in the womb is a human person)
Does that baby have the moral right to be cared for, even by a stranger? That is, does the stranger have a moral duty to care for a baby that’s not even his own?
Every truly moral person with even a sliver of a conscience must say, “Yes, that oerson should at least care for the baby until and unless it can be found a more permanent home or until it grows up to care for itself.” This then destroys #2.