I can't agree with either your premises or your conclusions here. First of all, you must be using some definition of "sapient" I'm not familiar with, because whales don't qualify for the term as I understand it. (And even so, hunting them has been internationally banned for other reasons.) Second, Kelpiens are unquestionably sapient — they use sophisticated tools and language — and I honestly can't imagine modern humans being comfortable eating any species with those traits. (Heck, the revulsion it evokes is precisely why it was (over)used for shock value in DSC.)
There's shock value, yes, but as with all Trek, perhaps there's more at work here.
Of course the viewer is horrified by the spectacle of those dastardly DSC Terrans dining on Kelpiens. However, Kelpiens are not actually real. They've been anthropomorphized enough that we wouldn't. Anthropomorphic aliens are a huge thing in science fiction in general, and in Trek in general (hello, Preservers). We know that's Doug Jones under all the prosthetics, and ew... we're not cannibals.
To the Ba'ul, and to Mirrorverse Terrans, eating Kelpiens makes sense. To many real-life human omnivores, eating cetaceans (whales, dolphins) and cephalopods (squid, octopi) makes sense. What is "revolting" to one human culture is a great delicacy in another.
Yet scientists have observed intelligence, communication, and even culture in whales and dolphins. They're studying intelligence in octopi. Even as far back as when STIV was produced, the fact that whales were sentient was part of popular understanding -- hence, the premise of the movie -- but more recently, scientists have studied whale language and culture.
‘
Whales and dolphins are ancient and wonderful sapient and sentient beings. How would we be judged by our great, great grandchildren and all unborn generations if, knowing what we do, we do not fight to prevent their extinction? The whales and dolphins need and deserve our help – now, before it is too late.’ --Jane Goodall
Sapient Cetaceans is an actual TV Trope as well, with STIV being a listed example.
We're starting to wake up. Whaling used to be a gigantic industry in the past. Whaling is how Arctic people sustained themselves. But in the 21st century, there's an international outcry -- the trend is moving toward leaving them alone.
By the 23rd century in our timeline, it's doubtful that any of our descendants will be eating animals. I expect that arguments against eating other animals, and using animal products, will eventually be won. I still consume meat and seafood, but in a century or two, we probably won't be killing and eating things, and the practice of doing so will be looked upon as barbaric.
We wouldn't eat Kelpiens, and we definitely wouldn't if our real-world First Contact was with a species like that. They walk upright, they have two eyes, they are graceful and tall and sound sort of like Doug Jones.
However, what if the first aliens we encountered looked more like whales or squid than us? What if they were tasty with marinara sauce? What then?
My point: If all Trek aliens are a commentary on some aspect of humanity, why then, even the Ba'ul (whoever they are) might be us. And not only the scary Worst of Us that we can push away...
us us, the parts of ourselves that have enabled human evolution, the messiness that is at odds with Gene's vision, and the stuff that the best of Trek helps us reconcile.
DSC's put some thought into this. Can't wait until Thursday.
