Well, Bicho, I don't think length matters. I have shortform (1-min) and plenty of other 3-min stories chosen for further distribution.
I agree with you that the Language Learning is a very well-written story.
Here's some food for thought - I'm reading Jessica Lynn's ebook about Medium success.
She suggests that, as a new writer, the faster you manage to get stories curated, the easier it will be to keep a high curation rate in the future. Same, the longer it takes you until you get your first stories curated, the harder it will be to have others curated in the future.
I can't say that it makes much sense to me, but Jessica is an experienced writer around here.
Now I'm going through my older stories stats and I'm surprised to see how things changed. Just noticed one early story that got even the "Distributed" tag on the views graph, one month after I published it. Guess I can now testify to those stories about stories distributed later.
Meet my Curator? Umm, I don't think I'd be eager.