While it is nice that chess.com gives a warning for aborting games, I believe players who conduct themselves in this manner should automatically forfeit the game. There's nothing more aggravating on this site than players who get lucky the first game, agree to a rematch, and then abort the moment they see you play 1.b3 or other offbeat lines. They know they don't know how to play against it, so they abort rather than allowing a tied match. This is cowardly unsportsmanlike behavior, and a warning isn't enough. You've already played the first move, so it needs to count as an automatic win on the spot.
While it is nice that chess.com gives a warning for aborting games, I believe players who conduct themselves in this manner should automatically forfeit the game. There's nothing more aggravating on this site than players who get lucky the first game, agree to a rematch, and then abort the moment they see you play 1.b3 or other offbeat lines. They know they don't know how to play against it, so they abort rather than allowing a tied match. This is cowardly unsportsmanlike behavior, and a warning isn't enough. You've already played the first move, so it needs to count as an automatic win on the spot.