We need moderators aggressively retitling articles submitted with stupid or biased titles. (Not only because that fixes those titles, but also because it reduces the incentive for submitters to submit with bad titles.) And if we have that, then inevitably there will be occasional misjudged retitlings. The question is whether the benefit outweighs the cost, and in my mind there's very little doubt that it does.
For what its worth, whatever was wrong with the original title I feel like yours was pretty misleading after going and reading the article (great article by the way, thanks for sharing it). The article was very explicitly about the library congress meeting to talk about the origins of the map, rather than a general piece about the map. If thats all you found interesting, perhaps you should have linked to a wikipedia page or a more general article.
I had changed it because I knew nobody cares about the Library of Congress, and no one knows what Portolan means. I read the story, determined a meaningful title, and the moderator decided that was no good. Since I have edited many, many newspapers, and written countless headlines, I felt particularly annoyed.