Have you read their dissents yet? Did they actually argue in favor of individual states setting their own unique immigration laws?
They argued that the states should be able to enforce (or not enforce), as the case may be, federal immigration laws.
What happens when we get a republican in office and CA chooses to turn a blind eye to federal enforcement of the border?
If the decision had held up AZ, it would shield CA as the state would be the enforcer.
There is a reason why naturalization was controlled by the feds in the constitution. It’s right there. Immigration is an enumerated power and thus not subject to the 10th.