That’s what I wonder too. Whose rights prevail? Airlines no longer give peanuts because people have peanut allergies. What about people who have allergies to dogs, cats, and horses (or whatever creatures are deemed service or support)? Does someone have to go into anaphylaxis, and likely die?
I have a friend who has asthma and severe allergies. She is allergic to cats; she can’t spend any time at my house because we have a cat. She and her husband were on a flight a few years ago when her allergies started acting up. She couldn’t figure out why. Then they noticed a terrible odor. It turned out that the lady in front of her had a cat in a basket and the cat pooped. My friend was NOT happy to be seated that close to a cat (and nobody around them was happy after the cat pooped).
I had a “therapy dog” come very close to biting my hand a few years ago. The owner of the dog took the dog with him everywhere and it was a problem (overprotective). He thought that because of the ADA no one could say anything about his dog. I did a little research and found that the ADA does allow for these animals to be excluded IF they are aggressive and/or they pee or poop in inappropriate places.
I think that at the very least the airlines should notify other passengers that there will be a dog/cat/horse/whatever on the flight and allow them to opt out of that flight without penalty. Seatmates should definitely be able to change seats or opt for a different flight. A few years ago, a flight attendant came to me and asked if I minded if they seated an unaccompanied minor next to me. It was a boy about 10 or so years old. I said of course not. He turned out to be a very pleasant seatmate.
Why should objecting passengers have to opt out? If you can’t go somewhere without your animal, stay home. Get a teddy bear.