I think that such possibility was even anticipated by ICE.
CRF, Rulings by Term, Actions wrote:Tapping a resource can only be done at a time when you could otherwise play a resource event.
You can play a resource event in any phase during your turn, you can play it also in opponent's turn during CvCC. However you cannot play a resource event in opponent turn in response to cc caused by Ren Unclean, so you cannot also tap Phial of Galadriel at this time.
ICE has decided not saying just that "Tapping a resource can be done only in your turn or in opponent's site phase during CvCC" leaving room for other possible situations where player is able to play resource event outside his turn.
My interpretation of "CRF, Rulings by Term, Actions" entry...