[F]reedom, reason and morality are intertwined; a corruption of one affects the others. If we hold that it is morally permissible to take innocent life on demand, then we have destroyed the moral basis for the obligation to feed, clothe, house and pay people a just wage. If some can be killed for arbitrary reasons ('arbitrary' means 'based on or subject to individual judgment or discretion'), then the moral obligation to value all others is fatally undermined as well.
Now, in the comments, this person ('S') explained that, no, they weren't actually calling pro-choice people murders who do not value human life at all, because 'murder' is a legal term. But I'm just going to run with the assumption that they were, in fact, talking about pro-choice people.
Let's start by breaking the argument down. I'm going to paraphrase a bit, and lean a bit on their earlier comments.
- Freedom, reason and morality are intertwined
- Abortion devaules certain kinds of life
- Hence, abortion devalues all human life
- Hence, pro-choice people do not believe we have any obligation to others
Now, let's ask ourselves what exactly this argument is supposed to do. Who's going to find it convincing? Well, clearly, it can't be some kind of reductio ad absurdum that assumes abortion is moral and tries to show that's a contradictory position: it immediately follows from (2) that abortion is immoral! That is, no pro-choice person (well, no reasonably thoughtful pro-choice person) is going to agree that abortion devalues any kind of life. (Interestingly, a commenter made this essential point, and that's where S said they were not, in fact, talking about abortion.)
So, this can't be an anti-abortion argument. But neither could it be the sort of asinine, self-aggrandizing rant wherein abortion opponents convince each other that pro-choice people aren't just baby-killers, they're downright sociopaths! Because, of course, everyone knows conservatives are way too tolerant, intellectually honest, and respectful of their liberal sparring partners to write anything like that.