I don’t think anybody is saying all babies conceived of rape should be aborted, only that no woman should be forced to carry to term a rapist’s baby if she doesn’t want to because that would be extremely traumatic. Frankly I think forcing a woman to carry an unwanted pregnancy to term would be traumatic however the child was conceived.
By the way, I don’t think the “if I’d been aborted I wouldn’t exist” argument is especially powerful. If my mum hadn’t miscarried a baby before me I wouldn’t exist. We are ALL only here through a twist of fate. And if you didn’t exist? Well, the world would still be turning.