For those who didn't get the reference to Omelas (including myself) it appears to be to "The Ones Who Walk Away from Omelas" 'a 1973 work of short philosophical fiction by American writer Ursula K. Le Guin. With deliberately both vague and vivid descriptions, the narrator depicts a summer festival in the utopian city of Omelas, whose prosperity depends on the perpetual misery of a single child'. [0]
If you want to dive into the philosophy... What is the relevant counterfactual? If the alternative to animals living in conditions below your standards is no animals at all, (or worse conditions), then I find pet stores to be morally good. If the counterfactual is happily living animals, or a world that is better in some other way, then you have an argument for me. But does banning pet stores create a place for happy animals? Or does it have some other effect that makes something else better about the world?
Me and people I've known growing up have found many, many friends in foster homes, vet offices, shelters, the street. Where profit motive doesn't really exist...
[0]: https://en.wikipedia.org/wiki/The_Ones_Who_Walk_Away_from_Om...