I feel like a lot of the answers here are missing the intent (as communicated to me in chat) of Calvin's question, so I thought I'd make my own. Let me start by clarifying something:
This question has nothing to do with whether the showcase should be closed/locked permanently.
(for voting and discussion on that visit the original meta discussion)
This question is did the mods prematurely close the showcase, and should it be temporarily reopened while awaiting community consensus.
The answer is yes: just look at the votes on the original. At the time of the locking, Dennis's answer in favor of closing as too broad was at about score 7, with about a 60-40 breakdown in upvotes vs downvotes. Meanwhile, the answer in favor of keeping it open were at about scores of 15-20 with more like an 80-20 breakdown in upvotes vs downvotes.
Even if you subscribe to the most literal definition of majority (or plurality I suppose in the case), this isn't much of a consensus. And due to the question itself being downvoted heavily, the voting sample was really small.
Furthermore, now that the showcase has been locked, a lot more attention has been drawn to the original meta question and the consensus of keeping it open definitely seems to emerging (additionally, my answer suggests the barebones of a policy for handling this in the future).
Regardless of whether you consider this to be a consensus yet, there's no denying that there was no real consensus at the time when the question was locked. I would now like to take a reading from
the Book of Atwood A Theory of Moderation:
As a moderator, your actions now represent the community, so you will
be held to a higher standard of behavior. You are an ambassador of
trust, with the same sorts of rights that the official development
team and community coordinators have.
Your goal is to guide the community with gentle -- but firm --
intervention. Respect your fellow community members at all times;
demonstrate fairness and impartiality in your actions.
Keep the site reasonably on topic by closing, migrating, or removing blatantly off-topic questions.
Our moderators enjoy a fair amount of free will, which our site has benefited from immensely in the past. However, this is one of situations where the moderators should act as regular community members and vote/answer, and only execute mod actions after the community has agreed on something. The showcase is clearly not a blatantly off-topic question -- we wouldn't have needed this discussion in the first place if it was. As a result, the showcase should have been left alone while awaiting a consensus or (perhaps) locked with the "ongoing meta discussion" reason. Instead, it was closed as too broad, locked for historical reasons, and a status-completed tag was put on the original discussion implying discussion is over (which has now been changed to status-review which is somewhat better). This is wrong.