Not a glitch! We edited it. But you're slightly mistaken about about the policy. It is "Please use the original title, unless it is misleading or linkbait" (https://news.ycombinator.com/newsguidelines.html). Note that "unless". The second clause is as important as the first!

"The erasure of Luigi Mangione" is a linkbait headline because it drastically inflates the scope of the article. Therefore we changed it, in accordance with the guidelines, using a representative phrase from the article body.