Sportsmanship

My daughter plays AYSO soccer. She is on a 7U team (7 years and under). Part of the deal with AYSO is how good sportsmanship is emphasized. Per their Players Code:

Play for the fun of it, not just to please your parents or coach!
Play by the rules.

Never argue with or complain about the referee’s calls or decisions.

Control your temper and most of all, resist the temptation to retaliate when you feel you have been wronged.

Concentrate on playing soccer and affecting the outcome of the game with your best effort. Work equally hard for your team as for yourself.

Be a good sport. Cheer all good plays, whether it is your team’s or your opponent’s.

Treat all players as you yourself would like to be treated.

Remember that the goals of the game are to have fun, improve your skills, and feel good. Don’t be a show-off or a "ball hog".

Cooperate with your coaches, teammates, opponents, and the referees - there cannot be any soccer games without them.

The bold emphasis is mine. K's team lost the game 5-2, but that was not the upsetting part. About midway through the first quarter, K was on defense, and one of the girls on the other team told her and two of her teammates that K's team stinks. I could tell just by looking at K's face that something was wrong, but did not find out what until the quarter break. K was crying. I told K's coach what had happened (and thankfully the second quarter was K's time to sit out). He let the referee know, who let the other team's coach know.

At the end of the game, the teams all line up and high five each other, but there were no apologies from any of the girls, nor the coaches. I know I should let it go, but I am really angry.