Bare in mind that the other reason noone wants to open that Pandora's box is that in reality the monarchy's interference is relatively minor and the political establishment (with full backing of the public) would permanently shut down any attempts to interfere in a more major way.
That's not too say that the guardians findings aren't troubling or that the powers the UK monarchy do wield aren't antidemocratic. But they're only ignored because they're relatively minor.
In the case of something major like a national security incident they'd be overruled and potentially trigger the dissolution or atleast severe weakening of the monarchy. They're aware of that fact and thus careful about what they do.
That's not too say that the guardians findings aren't troubling or that the powers the UK monarchy do wield aren't antidemocratic. But they're only ignored because they're relatively minor.
In the case of something major like a national security incident they'd be overruled and potentially trigger the dissolution or atleast severe weakening of the monarchy. They're aware of that fact and thus careful about what they do.