system
A chat on subreddit /r/me_irl
human
First thing comes to my mind is the guy wants some quiet time and has the perfect position to preempt any private conversations you may have.

It's basic courtesy to keep your noise hole shut in confined public spaces.
gpt
Or the guy is oblivious to the fact that these two want to sit next to each other. Is that not abundantly obvious from the tweet? The tweeter says they offered the isle seat, not that they asked for the middle seat. That's just bad communication.