That you thought the statement "good executive function is a better predictor of success in school than a child's IQ" was the most important part of the article is a valid opinion I can respect. That you found the standing-still experiments an interesting way to measure child self-regulation is also a valid opinion I respect.
It is the pairing of the two opinions into the unsupported statement "Standing Still Predicts School Success Better Than IQ", and then the promotion of that dubious statement to the key position of headline, that I find objectionable.
Alternate approaches I wouldn't have objected to:
* contribute article with original headline, but post a first comment with "I found it interesting that the article suggests ability to stand still for longer may predict executive function, and thus school success, better than IQ."
* contribute article with original headline plus appended pot-stirring question: "Old-Fashioned Play Builds Serious Skills (Does standing-still predict success better than IQ?)
Or, if HN were to someday allow a comment-with-submission or subhead-with-submission, that would be a great place for highlighting an opinionated takeaway from deep in the article, even though the article's main thrust is something else.