Except that a lot of the skaters DO follow each other on twitter. Like I said, Jeremy follows pretty much everyone on the team EXCEPT Jason. Also Jason tweeted a photo of him and his teammates (including Jeremy) a few days ago. All his teammates retweeted Jason except for yes, Jeremy. He chose instead to RT a fan's RT which I found a little odd. So maybe I am reading too much into things but I have a hard time believing that Jeremy and Jason are exclusive text buddies when as it it they barely hang out with each other unless it's in a big group setting. ...
I am aware that a lot of skaters do retweet each other tweets. But the fact that you actually have bothered to cross-check which Team USA skaters do and do not follow each other's tweets suggests to me that you might be placing too much importance on Twitter.
If you want to get technical and overthink Twitter even further, maybe Abbott does not follow Brown, but has included him on a private Twitter list. I do not follow some members of my own family, but they are on one of my private lists. And did you check whether Abbott's mother and/or sister follows the Twitter accounts of Brown's family members???....

(And of Brown's ponytail?

Just kidding, I know that last one does not actually belong to anyone from Team Brown.)
[And I hope (NOT) that you have been monitoring all the other social media too -- Has Edmunds liked more FB posts of Davis or of White? What does it mean that the Shibutanis did not tweet three of their Instagram vids? Does Chock have more Team USA photos on her Pinterest board than Castelli does? etc., etc.

]
(Not sure whether you understood about my usage of "exclusive" and maybe I am not understanding yours.
In case I was not clear, what I meant is that the Olympic skaters from Team USA belong to a text-messaging group that includes only them -- so that each skater can share texts back and forth with the collective group.)
I don't think Jeremy & Jason are that close. Jeremy in particular seems to prefer keeping his distance from Jason. He doesn't even follow Jason on twitter (though Jason does) and I've noticed that he won't reply to or retweet any of Jason's tweets . I feel like there's probably some rivalry/jealousy issues going on as far as Jeremy is concerned but that's just me. ...
In any case, I think it is a huge leap from an observation that person X does not follow person Y on Twitter ... to the supposition that X prob. has some rivalry/jealousy issues with Y.

No matter whom else X does follow. YMMV.
Jeremy and Jason get along great as do their respective families, who were referring to themselves as Team J (Jeremy and Jason). I know this from inside sources.

Additionally, Jason has gushed about Jeremy in many interviews. ...
Hooray for Team J!