I think you missed the point.
The ruling was that Alabama had to follow Georgia’s law.
Why not force Georgia to follow Alabama’s law?
No, you missed the point.
The ruling did not say that Alabama had to follow Georgia law. The ruling said that Alabama had to follow the Georgia court's ruling.
Georgia courts follow Georgia law in ruling on the status (marriage, divorce, adoption) of Georgia residents. If that status has been determined by a final court ruling in Georgia, other states must follow that court ruling if the people involved move to another state.
If you read the article, you will see that Alabama never even tried to claim that Alabama law applied here (because the adoption had taken place in Georgia). The Alabama court said that it was going to ignore the Georgia court's ruling because it thought that the Georgia court had incorrectly applied Georgia law. Alabama has no power to do that, which is why SCOTUS slapped them down 8-0. If Justices Thomas and Alito think you're wrong, you may be missing something.