This answer is locked https://judaism.stackexchange.com/a/1997/3350. However, the lock says it's a question lock:
Yeah, that's bad, not only from a display standpoint, but also from the back-end, which expects only questions to be locked with historical significance.
So, I've removed the ability to lock answers as historically significant, which was probably used to keep them from being flagged. To help combat new flags on locked posts, only the "other" reason will be available.
As for the answer you linked, I removed the historical significance lock and relocked it without a notice. Mods, feel free to make changes to that :)