>>Pretending that the 2nd Amendment was a restriction on the states<<
Not pretending. The constitution (and bill of rights) does not proclaim what rights the government gives individuals. Rather, it proclaims what God-given rights cannot be taken away by the government. This means that if the federal government cannot take away a certain right, then NO government under that umbrella can.
Conversely, if the constitution does allow room for the federal government to take away a right (like the right to rob), then local and state governments have the same right, even if the federal government is silent on the issue.
This appeal is clearly appropriate and is a textbook case of why the judicial branch was created in the first place.
The FEDERAL government.