This question was downvoted and closed, but I would like to know: How is it significant?
It has a historical lock because a former moderator placed the lock there. I don't know why he did it. I can't even begin to speculate. But removing the lock would change little: The question is terrible and the user isn't going to fix it.
There's probably still room for a good question along these lines, but this wasn't it. No longer seen in this post are several deleted comments where the poster explicitly stated it was a "test" question and people reacted quite negatively to that. Then he claimed it was based on a real situation, but refused to clarify it so that he could get a proper answer.
I'm pretty sure we'd lose just about nothing if the question were deleted. If anyone else has seen it since the week it was posted, I'd be surprised.
As suggested in comments, it was locked to prevent it from being bumped to the front page ("active" questions view) when I retagged it. At least as of when I last had diamond privs, unlocking a question was one of the actions that bumped a question to the front page, so it stayed locked.
No sense in stirring that turd back to the top that I could see, but perhaps the current mods will feel differently.
The question is not very valuable in its current state. There is however one reason I won't vote to delete it. Deleting the question would also delete the answer.
The answer which was given to that question is a good answer. And that answer would also be applicable to more realistic questions that might come up. So there is a possibility that somebody may search for an answer and find that answer useful.
But it is not the question and answer I would consider to deserve the historical question notice. The scenarios where that notice would be most applicable is good questions with good answers which just happens to be off-topic according to our current standards.
The notice has since then been removed, and I think that is all that needed to be done about that question.