The SCOTUS is just as bound by our Constitutions clear words as any other level of gov't in the USA.
A 'decision' by them, - claiming that our rights to own and carry arms can be infringed by 'reasonable' [health & safety] 'regulations' will be unenforceable, just as booze prohibition was unenforceable.
Fiat prohibitions on guns, booze, drugs, whatever, -- are unconstitutional under our concept of 'due process of law'.
As Justice Harlan recognized:
" -- [T]he full scope of the liberty guaranteed by the Due Process Clause `cannot be found in or limited by the precise terms of the specific guarantees elsewhere provided in the Constitution.
This `liberty´ is not a series of isolated points pricked out in terms of the taking of property;
the freedom of speech, press, and religion;
the right to keep and bear arms;
the freedom from unreasonable searches and seizures; and so on.
It is a rational continuum which, broadly speaking, includes a freedom from all substantial arbitrary impositions and purposeless restraints --"