According to the article the coaches took it in good humor since it wasn't a super serious meet, but said he "wouldn't get away with it" at future meets.
As a former high school coach, I'm curious how others would react. I feel like I'm pretty intense and could be a bit of a hard ass so might have wanted to ream this kid out. A race should be serious and this is making a joke of it. Besides making a joke out of it, he clearly compromised his own race by sprinting out front of the field to take this "selfie".
On the other hand, doing that would come across as "not being fun" or "easy going" and you might turn certain runners off from joining the team or having fun with it if you're too serious for them. Sounds like this kid sucks, but it just as easily could have been a really talented runner who just didn't take it that seriously.