I agree. And, it seems to paint Justice Scalia as sort of a madman, even though the author has laid out plenty of reasoning as to why there could be different answers, the author believes that any confident, unqualified answer was wrong, and Scalia should have begun a debate instead.
And it seems to also indicate that Catholics are madmen for following the Pope, who might be wrong about fish. Well, guess what.
This is a linguistic question, and it has origins that date back before Jesus's time and among non-Christian pagans in all sorts of places. Let's look at Europe and Latin.
In Latin, carnem means meat. But it is specifically flesh meat, that is: beef, pork, chicken, etc. It is an umbrella term, and of course there are more specific words, but carnem is a class of meat, and it is associated with the human flesh, and this is why we abstain from this type of meat on Fridays.
Carnem excludes fish. In Roman Catholic discipline, we abstain from eating land animals and birds. Animals that swim in water (some opinions say, cold-blooded) are in the "fish family" as far as we are concerned. Guess what? Alligators are fish. Muskrats, beavers, and capybaras are fish. Call me a madman if you wish. I am just classifying things according to the faith. Try having this conversation with an Orthodox Jew.
https://www.catholicnewsagency.com/news/26593/alligator-ok-t...
https://www.mentalfloss.com/posts/lent-beavers-muskrats-capy...
I think what a canny debater would first do is define the terms. I would've asked the questioner: "How do you define meat? Give some examples and counter-examples. How do you define fish?"
Over-confident? Perhaps, but wasn't that supposed to be the tone of the meal, with a confident Justice welcoming new recruits?