Maxperson
Morkus from Orkus
While your Rule 0! is a very narrow instance of form R(the real Rule 0), it's an abusive and very little used instance. Sure I have the power to tell Johnny that no his PC doesn't really pick his nose, but why do that? Rule 0's function isn't veto. Rule 0's function is to alter the rules by adding, subtracting or changing the rules in order to make game play better or more enjoyable.I don't see the stretch of water. I don't see how what I posted (what you have called Rule 0!) is not a particular instance of your general form R. It assigns a capacity (power) to a participant. That power is governed by regulatory principles/rules (such as the need, when pressed, to refer to rulings and/or fiction).
This is why, as I posted, I have not made any particular assertion about "rule-changing rules" (which I think should, within Suits' framework, be characterised as a form of power-conferring rule). Whether or not they are candidate lusory means is not content-independent.
I'd also argue that you don't need to use Rule 0 for veto power. Take 5e for example. The rules for ability checks give the DM the explicit ability to grant automatic successes, automatic failures(veto) or call for an ability check and assign it a DC. Unless the DM is abusing his authority, whenever he veto's something the player does, there's a rule and good reason to back up that veto.