There is nothing that says HN submissions need to be from the current date.

To add to what arcticfox correctly said: we put the year on articles from previous years but this one is from earlier in 2017. Historical material is super welcome here too.

The "News" in "Hacker News" is like a second-hand clothing store in my home town called "New to You". Of course this article didn't qualify in your case, but that's the general idea. Older posts can't be new to all of the people all of the time but in the long run there are enough surprises to go around.

One would hope that discussions about whether repeating old news is interesting or not is encouraged.

HN's definition of 'interesting' is for practical purposes pretty established. Of course we don't all agree, but there's enough of a stable core that I wouldn't say it changes much.