Can I check this unilateral closure?
Doesn't it still relate to history, notwithstanding "a figure of speech, the implication of which is explained right afterwards in the source quote"?
Just because something was written in the recent past, does not mean it's necessarily about history or in scope here. History.SE is not a service for explaining simple English sentences which can be understood independently of any historical context.
Again, the original source explained what the quote means in the very next sentence.