No.
This was the seventies. People didn't do jokes about crap like that back then. Not on the Carson show anyway.
True. I remember a Mexican comedian who got the bum's rush after 10 seconds into his bathroom humor routine. Willing to bet is was the shortest appearance of any comedian on the Carson Show.
I'll be 60 years old next month. I remember the bit. It was not accepted by the audience because of the subject matter (as you suggest) ................ AND because it was a poorly constructed joke. How does one "demand an abortion" AFTER the baby is born?
Get real. Joan Rivers blew it two different ways.