The big difference I see with this one is that the young lady, despite Down syndrome is older than her competition. Just like I don't think I would be allowed to compete in a younger age group when I was that age either.
Granted, I don't think she has an unfair advantage and this instance sounds more like they are adhering to the rulebook. Did they still not allow the young lady to compete even after her team proposed that they would accept a loss in all of there games despite the outcome?
Her team would accept lose all games only to allow her to play.