vegan

I understand the thought process, but I don't think carnism is based on "They're too weak to stop me"

Not OP, but I don't think he's saying carnism is "based" on that presupposition, rather it is ultimately the justification that allows for the objectification of something that undeniably possesses sentience. It is the point of failure in the supposed reasoning that most carnists would use as their rationale for not doing to humans what they readily do to animals.

Just as you might not eat an animal due to e.g. its capacity for suffering. A carnist wouldn't eat you due to your being a human.

But that's just it. Why did you change the second sentence to "a carnist wouldn't eat you due to your being a human" rather than stick with the reason you gave for a vegan not eating an animal? Yeah, a vegan wouldn't eat an animal due to that animal's capacity for suffering, but so too, a carnist wouldn't eat a human due to their recognized capacity for suffering.. The fact that you further distanced the carnist from the root of the issue as you already stated it (empathy - the recognition of a capacity for suffering) by making it about "being human" is very telling. Why should the humanness matter? Ultimately it's because (or it should be - it's what most would claim is because) we empathize with other humans - we recognize their capacity for suffering. What is it about an lifeform being human that stops we modern people from thinking it's ok to objectify humans to the extent that we would be ok with slaughtering them because they taste good? Empathy - the recognition of their capacity to suffer as we ourselves do. But many non-human animals who carnists still are ok slaughtering because they taste good have that capacity to suffer too, and that is where the carnist's disconnect in their stated reasoning occurs, that is where BeanisBrain is pointing out that the carnist is failing to live by the thing that they (and generally we as a society) claim is what matters when it comes to other humans - as a human I know other humans suffer. We are now at a point scientifically, philosophically where we can say with the same certainty as the previous statement that as a mammal I know other mammals suffer. So carnists have to come up with other excuses, often telling themselves the lie that these non-humans don't suffer, but it is too obvious of a lie that they don't on some level recognize it as such, so doing so reveals that ultimately, it is not actually their empathy that keeps them from harming other humans, because that empathy fails when it comes to creatures that don't lack the capacity for suffering but only DO lack the capacity to stop the carnists from objectifying them, ignoring their suffering, and slaughtering them because they taste good. I'm really tired, inebriated and I know I've been repetitive and less than perfectly cogent, but I really hope some of this has been enough to shine some light on how your comment is really proving OP u/BeanisBrain's point.

Nobody's calling for the consumption of orphan children.

u/tomenzgg beat me to it, but apparently you haven't read A Modest Proposal.