I don't know, I was actually thinkin' what RedGoldStag said before I even read his post. It's possible that the sequence could go like this:
1.
Terrible as the Dawn is played
2. Free Peoples player has the option to prevent the effect of the card being played.
3. If Free Peoples player prevents, Galadriel is fine, and the sequence ends here. If not, go to step 4.
4. Free Peoples player chooses not to prevent the effect of the card. Galadriel wounded.
5. Free Peoples player has option to respond to wounds being placed, potentially preventing them.
I'd think that
Steward's Tomb would only disallow step 5 of the sequence.
But, realistically, I could see it going either way. =P