It's not a "made up title", Google did in fact fork Swift on GitHub. That doesn't mean anything in an of itself, thousands of people/organizations have also done so, but it's mildly interesting since it's Google, and because it was posted here, we now know why.
The problem is that "fork" means two different things at this point. Compare "FFmpeg developers fork FFmpeg" in the sense of "...and create libav" and in the sense of "...so they can submit pull requests." One is extremely newsworthy, one is extremely not. If you're posting something to HN, it's a reasonable assumption that readers will think you're posting a newsworthy thing as opposed to not.
How do you know the intention of a fork without their own explanation? It was unknown at the point of posting, and posting title is still technically valid.
This posting let you know their intention. Isn't it newsworthy?
"Google employees are contributing to another project" is not newsworthy, no. Neither is them creating a github fork unless you have evidence that they do not intend to use the fork for the main reason people create GitHub forks: contributing.
No, that doesn't make sense. You didn't think they merely made a github clone - as you yourself said above, you thought Google was going to make their own version of the language. You posted suggesting that they are. But it wasn't true. People working at Google had to correct you. Other users flagged your post into oblivion. Those thing wouldn't have happened if the title wasn't wildly inaccurate. You should have tried to find out if it was, instead of posting an inaccurate thing on HN.