Actually, it is not a strawman... I have debated with at least one person in this very forum that holds the position that the fetus is part of the woman's body. I suspect it is an uncommon position to hold though...
Actually the position is not that uncommon one among medical professionals, I even gave 8 biological factors that objectively evidenced this to be the case, but of course they were never addressed honestly, just dismissed with the usual emotive handwaving.
However it is still a straw man, since that argument supplied with sufficient objective evidence (see above) was offered to contradict the claim that a blastocyst or foetus is an independent human being, but not as a justification in and of itself for an abortion. Since I am pro-choice, and it's none of my business why a woman chooses to terminate a pregnancy, why a woman seeks one is irrelevant. If a woman ever makes the choice to simply mutilate a foetus, and astonishingly a medical professional team agree to do it, with the intent to take the pregnancy to term, then I will address this use of reductio ad absurdum. Until then it is an irrelevant red herring that yet again tries to ignore cogent facts and rational argument with an appeal to emotion.
Women are not prosecuted for smoking or drinking during pregnancies though, so even though this is an obvious reductio ad absurdum fallacy, it is not very compelling even without being manifestly irrational. At least this is the case in the UK anyway.
The OP is again simply comparing an insentient foetus or blastocyst with the rights we grant fully sentient humans, in a dishonest and emotive use of reductio ad absurdum. With an example that is manifestly a red herring. Women it seems already have this right, since they are not prosecuted for harming a foetus by things like alcohol and drug abuse, or smoking.