“Who” is more often identified with individual/identity than sentience. They’re not talking about particular, individual cats.
I'm not sure there is any grammatical rule for this, though. And besides, nobody likes people that nitpick ;)
If the intent and meaning came across and the intention wasn't to offend and the meaning is clear there is zero and I mean zero need to pretend to be offended. The cat doesn't even care and clearly no body here thinks of cats as Bluetooth speakers... what practical purpose does any of this serve? None.
It's all part of that pronoun thing started by transgender people. The desire to be recognized as a certain gender in language codified into a "law" and that law is now being taken to logical extremes in such a way that we have to use the correct term for cats. The next step is to teach cats English so they can actually be offended.
My problem is other people having arbitrary problems with language.
On the other hand, above I just wrote "I am a foreigner that ..." and Grammarly corrected me to "I am a foreigner who ...". I am still leaving this comment here as a reference to others that wonder the same.
Nevertheless, in formal, written English, “who” is the overwhelmingly correct choice. Cf https://books.google.com/ngrams/graph?content=people+who%2Cp...
When it no longer even sounds wrong to well educated well-read native speakers, it’s pure prescriptive conservatism to hang on to the idea that there’s a grammatical rule there.
I think there’s a stronger instinct to use ‘who’ in preference to ‘which’ in these kinds of constructions - but overall in English both who and which are frequently replaced with ‘that’ in contexts where that previously would have been considered incorrect.
I think it's more permissible when it is used to emphasise that the cat as a living being is exercising agency in voluntary behaviour that they enjoy. (1)
e.g. "Cats that shed" or "rocks that crumble" vs "Cats who fetch" and "people who sing".
"Cats that shed" is definitely correct. "Cats who fetch" implies that the cat has agency and choice here, is in a small way "human-like".
Also the cat doesn't even care, it's not cats getting offended it's just people.
This is better bait for a pedant then a laser pointer is for a cat...
Besides, cats objectively have fewer rights because I can own one, for example.