Agreed. Just to add to your point, snipping off the reproductive organs of said pets also feels cruel to me. Almost to the point of owning a living toy for your amusement.
You want to encourage this outcome even more?
IMO, it’s better that the animal lives a good happy life with their human(s) and doesn’t contribute to pet overpopulation.
And if the human(s) in question need more companion pets, then they can go back to the shelter again and rescue the next one(s).