You don't HAVE to make arguments that invalidate the personhood of anyone with a developmental or physical disability.
You don't HAVE to insist that, actually, nihilist anti-natal horseshit is based, because humans are "the real virus" or whatever.
You can be a normal person!
You can be pro-choice because draconian abortion laws don't work, because you believe in a woman's right to make the decision, because you're worried about the end result of giving the government this much authority, or any other reason that won't boil down to "actually you can't be human unless you meet this particular criteria which, unfortunately, a lot of people who aren't fetuses anymore still don't meet."