Sorry, you're being intellectually dishonest on this one. Organs are formed during fetal development, not after sex. So how about we DO start with the truth.
A fetus is part of a woman's body. I said nothing about organs.
That was the premiss of the OP, Chomsky claiming the fetus was an organ of a woman's body. We both know that is not true. If I misunderstood your intent you have my apology.
I don't agree with him. To me, an organ is something which is in your body when you are born and remains with you forever. Something that is in your body for a short period of time does not meet the definition of 'organ', at least IMO.