The rules around titles are to always use the title from the article.
In general, that is the rule.
The cynic in me couldn't help but notice that an article with the original title "One of a Kind: What do you do if your child has a condition that is new to science?" has been on HN's front page for a day now with an alternate title.
For some reason, the same mods who removed "Feynman" as "click-bait" that is "not the title from the article" don't seem to have a problem sticking with the alternate title "Thanks, HN: You helped discover a disease and save lives" [https://news.ycombinator.com/item?id=8050106].