And for my own FAQ, here's what I put:
[Q] Can the Lani Iron Throne be used to cancel the effect of an out of play character ability like Royal Entourage?
[A] No, the Lani Iron Throne only cancels character abilities and that requires that the effect is triggered by a card in play. In the case of the Royal Entourage it is only a triggered effect and not a triggered ability thus it is not cancelable by the Iron Throne
[Iron Throne]: Response: Kneel the Iron Throne to cancel a character ability just triggered.
Also, it is important to remember that the "one response per trigger" rule is also defined in terms of "ability" - so it only applies to cards that are in play when they are triggered. Unless a specific limit is written on the card itself, there is nothing stopping you from triggering Responses on a card that is not in play multiple times.
I see, so even if someone were to cancel it, it would stay in my hand and I could trigger again as my next response. For reference here's the FAQ on the "one response per trigger":
(2.4) Responses Per Trigger
If a response or passive ability is triggered, the effect can only occur once per trigger. For example, if Sansa Stark (CORE S9) is in play and you play an attachment on her, Sansa Stark's effect (draw a card) can only be triggered once. (If a second attachment is played on Sansa Stark, her ability can be triggered again.)