This answer should be marked as community wiki or another one should be posted as such in its place.
The thing is general practice with these sorts of posts in the past has been to post an initial answer as Community Wiki and then other users edit it. For example see these:
- Who is who on this Doctor Who Christmas Card?
- Can we identify all the characters in this “Ultimate Space Battle” poster?
- Can we identify all the characters in this Universe 113 poster?
Therefore, it is highly likely that these users just assumed it was already a community wiki answer or didn't notice if it is or not. Whether this is acceptable behaviour or not is debatable but considering common practice I would say it is.
I have currently flagged for moderator attention to turn the answer into a community wiki one considering the mass community effort that has gone into it. However, if this is declined we should really create a new community wiki answer for people to edit instead of this users answer.
As for if this should be closed as Too Broad, no it should not. List questions that are finite and reasonably scoped are fine.
However, finite and well-scoped list questions are allowed here.
Note: This answer is addressing this specific case only not the general case of treating some normal answer as Community Wiki.