I really think the argument could go either way, but I'll just go ahead and play devil's advocate regarding Elessar's post, because I like doing that, and NO ONE CAN STOP ME!
(Well, except a moderator. But that's not the point!)
Anyway, the example quoted from the rulebook isn't really related to our scenario here. The rulebook is saying, "If an effect asks you to do A or B, and you choose A but then prevent it, you now have to do B." In more exact terms, it's saying, "If you choose to wound the Ring-bearer (A) instead of adding threats [B) from the
Morgul Destroyer, and then you prevent the wound to the Ring-bearer (A), you now have to add threats [B)." Essentially, it's pointing out that one of those two things HAS to happen.
So what happened was this:
1. Choose A or B
2. Select A.
3. (Optional): Prevent A
4. If you prevented A, you must now do B.
With our
TATD scenario, we're saying, "When given a choice between discarding Elves (A) and wounding Galadriel [B), we choose to discard Elves (A)."
Meaning we did this:
1. Choose A or B.
2. Select A, discarding your elves.
Since we have no way of preventing our elves from being discarded after we've committed to that, the scenario ends here. As you can see, the
Morgul Destroyer scenario in the rulebook is trying to cover an entirely different problem.
Basically, I'm not doing anything to prove either point with this post, I'm just saying that I don't think that the
Morgul Destroyer excerpt from the rulebook applies here. =P
EDIT: Had to change to [B), because ( B ) was turning into a skull. =P