The Supreme Court case of Morrison v Olson ruled on the constitutionality of Independent Prosecutors appointed pursuant to a congressional statute, which provided specific statutory roles for the AG, the courts and congress with respect to the special counsel. That statute expired.
The Special Counsel on the other hand is a different legal animal entirely, created under no congressional statute but solely under DOJ regulations, and presents a different set of legal issues.
I dont think so. The same issue of the need for senate confirmation will result in the same conclusion because the judicially determined classification as an inferior officer remains the same. Whether appointed by law or regulation (which by the way has the same force as law) the fact that the official is inferior is what determines if senate confirmation is required. Or so that is what the Supreme Court has ruled. Stare decisis makes this determination irreversible case law on this isuue. Your argument that genesis of the appointing power is determinative was not what the court ruled was correct. And since the USSC decides what the Constitution requires I would suggest that their interpretation is the correct view of the law in this instance, and not yours. Just saying.