(1) IF, it is constitutional that the gov’t can force the woman to carry pregnancy from rape to term,
(2) THEN, it is constitutional that the gov’t can force person A to provide his/her body for use by person B (generalization of (1) due to equality under the law)
(3) THUS, it is constitutional for the gov’t to force YOU to provide YOUR kidneys for MY use.
Do you like that prospect?
Your (1) is faulty. You’ve written it to be sensationalist, not accurate to the situation. But the actual logical error comes in at (2), where you slightly change the assumption from #1.
Here, let me re-write it for you in less sensationalist, more straightforward terms.
(1) If it is constitutional that the government can prevent a woman from ending a pregnancy
(2) Then, it is constitutional that the government can force a woman to become pregnant.
Do you see the mistake you’ve made? In the first case, you talk about an action the government won’t allow, but in the second you talk about the government making a specific action. That’s not a jump that can be made here logically. Here, let me formulate that with a different example to make this more clear:
(1) IF, it is constitutional that the gov’t can force a gay person to continue being unable to marry their same-sex partner,
(2) THEN, it is constitutional that the gov’t can force person A to marry opposite-sex-person B (generalization of (1) due to equality under the law)
(3) THUS, it is constitutional for the gov’t to force YOU to marry ME if we’re of the opposite gender.
That’s not a perfect analogy but it gets my point across: the government preventing one action doesn’t automatically give the government the power to perform a different action.
EDIT: Here’s a better example, a bit closer to the subject matter than I’d like but hopefully it will make sense to you:
(1) IF, it is constitutional that the gov’t can force a parent to not abandon their child,
(2) THEN, it is constitutional that the gov’t can force person A to provide for baby B (generalization of (1) due to equality under the law)
(3) THUS, it is constitutional for the gov’t to force YOU to provide YOUR time and money for MY baby.