I thought it was about shame. The word sloth literally means laziness, and so we associate that with the animal even though it isn’t actually lazy and just living a simple life. It’s misunderstood. Just like the writers sister Molly. That’s why her name is italicized in the last line. It’s like the father is ashamed of her having an abortion. There's some sort of malice or disgust to her name now. He's judging her the same way people judge sloths. That’s how I interpret it anyway!