I see very little damage in new users answering old questions. This is an easy and "safe" feeling way for a user to start transitioning from lurker to active participant, and the cost of having a question bumped is pretty low. We don't want to encourage repetitive answers, but we don't need to forcefully prevent them either.
Attempting to lock old ...
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.