Yes they did. Their decision was reversed by the U.S. Supreme Court, but they did indeed incorrectly find that law violated Millers rights.
"And reading the Miller court makes it fairly clear that had anyone been present to argue Millers case, the SC would have upheld the lower court."
If they would have been able to prove that a weapon as short as Mr. Miller's sawed-off shotgun was used by the average soldier, the U.S. Supreme Court may have ruled differently. We'll never know.
You of anyone should know that the decision was NOT reversed; the issue was remanded for further evidence gathering.