The title should accurately represent the article, even if it turns out the article is wrong; anything else would be editorializing. So even if it turns out the factored subkeys are phony, this article doesn't say that, so neither should the title. The top two comments provide a useful correction.
So, the current title seems fine. If anything, the question mark is a bit of editorialism.
The HN guidelines (and longstanding practice) are to prefer the article's title unless it is misleading or linkbait. A false title is misleading.
We sometimes add a question mark when a title is disputed but it isn't clear what a good (i.e. accurate and neutral) title would be. That's the best I've got until someone suggests an accurate and neutral title.
