This is supposed to be a clever lib-gotcha, weaponizing their own bleeding-heart position against them.

“I thought you said slavery was bad! How can you be anti-life then, since it’s just discrimination against a class of people, hmmm”

The reason it confused you is that there are so many mental gymnastics here that Larry Nassar woke up in a cold sweat in his cell. It’s such an unbelievably bad argument on so many levels that your brain won’t even allow you to consider the actuality of it. Unfortunately, this strawman reached the end of the yellow brick road and never challenged the wizard, so they never got their brain and live in a fantasy land where this is the pinnacle of debate.

In the end it’s the same old shit - reductive, misleading, but if you’re a moron it’s built on just enough factual information to get you to skip right over critical examination and just go “HA! Good one!”. You know; propaganda.