It was locked to prevent a rollback war, and to prevent users from defacing the post, which you can see in the edit history.
Unfortunately, locking a post locks all aspects, including votes, but sometimes it's necessary when people are feeling destructive.
Yes, definitely. Most locks should be temporary, especially in the case of edit wars. I have removed the lock, hopefully the question won't have to be locked again.
As a side note, a flag on the question would've been fine too, rather than a meta post. (unless locked posts can't be flagged, but I'm not aware of that being the case)
The reason for the question off-topic is being opinion based. Per our guidelines, a question should be objective rather subjective to be on-topic. Even though is off-topic, it attracted many views, upvotes, and overall good information for future viewers.
From what I have seen, an off-topic question may be good in general terms, but they attract downvotes ...
After reading over the question several time, I finally noticed the top box says that the question is no longer accepting interactions.
Apparently this is the new wording for saying that a question is locked, though I find it much less obvious than it was prior.