I think before ScummVM the only sane option of running Neverhood was Wine in Windows 95 mode. And that wouldn't help Windows users, so yes, GOG could be waiting for something else to materialize. ScummVM support was added in the end of July (in the release, master branch got it a while earlier) and since GOG were quite busy with tons of stuff they didn't get to it. I guess if there are no blockers from EA side GOG can get to it now. They never commented on this issue though.
In any case, both GOG and EA know thousands (at least according to the wishlist; it's probably closer to tens of thousands in reality) of people want the game here.