I think the author is just honestly trying to equivocate freezing shrimps with torturing weirdly specifically disabled babies and senile adults medieval style. If you said you'd pledge like 17$ to shrimp welfare for every terminated pregnancy I'm sure they'd be perfectly fine with it.
I happened upon a thread in the EA forums started by someone who was trying to argue EAs into taking a more forced-birth position and what it came down to was that it wouldn't be as efficient as using the same resources to advocate for animal welfare, due to some perceived human/chicken embryo exchange rate.
This reference stirred up some neurons that really hadn't moved in a while, thanks.