Firstly, I have been more or less happy following this site because it is about PHYSICS. I had a professor in College whose face would light up just by saying "Physics" .
Secondly I am aware that this has a long term goal of being a repository of interesting questions and answers to be found by future searches on the topics.
Thirdly I am aware that in education, as in most human organized goals, there are two tendencies a) follow the rules and you cannot go wrong, b) nurture the student and the knowledge will root and flower.
Actually the happy medium is the best in education. There should be rules and goals to challenge and channel, and there should be nurturing to generate spontaneous creativity.
If the site wants to be a web educational resource it should also keep the happy medium. Following strictly the rules is for games like football and cricket.
Leave everything ambient and impulsive may be good for poetry and the arts.
But physics at its best is stifled by football rules and regulations because the best physics comes out of creativity as great as the one Shakespeare showed in writing his plays.
What I am trying to say is that strictly sticking to rules stifles creativity, and educating physicists, who are mainly boys and mostly trained to follow the rules should have enough leeway to allow creativity to emerge. For example: closing "stupid" questions of young boys without looking at their profile or guessing their age, or leaving a kind comment, stifles creativity, no matter the rules, and discourages young people from following the field.
This is one reason I would "bend the rules" because we are not playing chess here. We are teaching and learning.
Now for this specific closure, that is not even reviewable, I think the blind following of rules is not useful. An aspiring young physicist googling for "best physics lecture notes" will get this on the search. Does it reflect well on the site to have it "closed as out of topic?" Would it attract him/her to have a look and contribute to the site? I think it would be enough to keep it locked so that it does not pop up on first page, and leave it at that. Not many people come out with "best physics lecture notes" questions to make it a problem, and if they do they can be referred to the duplicate.
Balance is everything, and remember, it is not a site for football games judgment.