Pretty much exactly that. The Government can (and does) request a Privy Council meeting, which issues various kinds of Orders in the name of the Queen. The Queen's Speech is another (less instrumental) way of government using the root account directly.
(Or, I suppose, you could `$ sudo su`and then `# instantiate_republic` to permanently promote the usual administrator account to root. Still not clear it's wise to directly govern from account 0, though).