It's definitely immoral for a city to have laws that make it impossible for working class people to live there (e.g. a suburb with moderately expensive land that bans multifamily housing and has large minimum lot sizes).

Whether it's immoral on an individual level to move to such a city is debatable. It's not unreasonable to want to raise your children in a community with low crime and good schools. On the other hand you could argue that choosing to move to a city with immoral laws is itself a way of supporting those laws, and in doing so you become partially responsible for their outcomes.