Holy moral absolutism batman, this barely reaches Sunday School levels of ethical thought. I'm a strong proponent of abandoning animal product dependence but poor-puppy-dog arguments drive me nuts.

For starters, every living being has a prerogative to survive and propagate its genetic pattern; pleasure and pain are base mechanisms for that. I personally refuse to believe that there is anything inherently bad about the existence of pain any more than the existence of pleasure is inherently good. Our human aversion to inflicting undue pain is natural as prosocial animals but that doesn't make it morally just or our tolerances for violence absolute.

Our reactions to violence aren't universal because every plant and animal has a set of characteristics which overlap with human characteristics to varying degrees. Those overlap very little with plants, more with mammals, even more with domesticated animals (selected for prosocial traits) and most with primates.

Moreover, our sensitivity to those traits is highly personal, depending on the context of our exposure to them. If your only exposure to non-human mammals is pet dogs then you'll obviously draw parallels when you see cattle with eyelashes and fur and tails. If you have to deal with dangerous feral dogs and nuisance vermin then you won't have the same sensitivity to those traits.

Our society exists at the expense of other forms of life, either directly (animal husbandry) or indirectly (habitats disrupted by our infrastructure). So saying nobody should eat meat because it causes suffering doesn't say anything about universal ethics, it's an unexamined exclamation that tells more about your existential dissonance than mine.

Before you dive into an argument about minimizing suffering, let's look closer at this part:

There is no way to rationalize eating meat in modern society as anything but catastrophically unethical

Humans have already destroyed many food chains, usually by eliminating apex predators. If there's nothing to hold the deer population in check, native plants will be decimated and the ecosystem will collapse. Humans are left in the position of culling them as the apex predator, the violence must happen either way.

How could eating the meat be "catastrophically unethical" in that situation? That's the expected flow of the food chain. Is it better to self-flagellate by disposing of ready calories; wasting water + topsoil + time to turn it into a vegan food?

Putting aside "humans greedy and meat bad", let's examine a fun part of your argument:

we cause immense suffering and death at a scale and acuity worse than the holocaust

We have 8 billion megafauna primates on our pale blue dot. Any pain we inflict is necessarily going to be at an immense scale. The scale has no ethical bearing unless you're arguing against utility derived, in which case a genocide is infinitely worse because we derive no utility from it.