Originally posted by Jorge Monteiro:
The trigger belongs to the NAP.
He allowed for AP to cast a spell AFTER saying the trigger would resolve. Assuming that it was done in a calm pace not trying to rush the trigger being missed (maybe this should have been more clear in the OP), I'd consider that NAP might have decided to extort only after seeing the opponent's plan.
I don't see how. Your scenario was…
Player N has a permanent with extort and casts lightning bolt on player A.
Scenario A.1:
Player A says “in response to bolt” and casts counterspell
Player N pays for extort and buries the bolt.
…and in the situation, Player N was paying for extort then letting the Counterspell resolve. In actuality, unless Player A specified he was acting after the extort trigger resolved, then Player N paid for the trigger “too early”, since extort normally requires a payment as the trigger would resolve.
The MIPG is pretty clear on this point…
A triggered ability that causes a change in the visible game state (including life totals) or requires a choice upon resolution: The controller must take the appropriate physical action or make it clear what the action taken or choice made is before taking any game actions (such as casting a sorcery spell or explicitly moving to the next step or phase) that can be taken only after the triggered ability should have resolved. Note that casting an instant spell or activating an ability doesn’t mean a triggered ability has been forgotten, as it could still be on the stack.
…so, up until the point Player N clearly takes an action that would normally only happen after the extort trigger resolves (say playing a sorcery or a land), then he can demonstrate awareness at any point. Certainly he can pay for extort prior to actually letting the Counterspell resolve, especially if he performs the actions at nearly the same time. (Paying W or B and putting Lightning Bolt into the graveyard.)
Scenario B is OOOS, not MT.