I didn’t keep the link, but from what I read, the dog was in an approved bag and all other rules were followed for the dog to be able to stay with the passenger, who was supposed to be allowed to keep the dog under her seat. The dog was also a puppy, less than a year old, and it probably just suffocated in the overhead compartment, which doesn’t get much air because it wasn’t designed to store living things.
If the dog was supposed to be allowed under the seat, why would they tell the passenger to put it in the overhead compartment? Just for the fun of it??? I don’t get it.