Mmm...not necessarily. Sanctuary only stops the
current quanta pool from being manipulated, which currently of course, has no difference. There's some question in my mind, though, if this was ever implemented, that the quanta produced would still go to the caster. It's like this: Sanctuary protects quanta pool (Q). New quanta produced isn't in Q yet, so while it's outside of the Sanctuary, it gets siphoned off to the opponent. That's a question for other people than I, though.
I do like this idea a lot, I just don't see much use for it right now.
Have you SEEN arena decks lately? Let's see here; slowing Fire rushes by a turn, taking advantage of huge numbers of opponent's early QTs, use thrown in with other denial cards such as Black Hole, Pest, and Earthquake...granted, it's not going to stop an opponent in his tracks, but having the opponent be deprived of even a single turn's worth of quanta can throw some decks off their game, and give you a vital extra turn to get your defenses in gear.