I know it doesn't seem like a big deal, but if my CP had something like that in a dance dressing room I would be quite upset with her - I hope she'd know better, but you never know ;/. You always have to be very careful what you say around fellow solo competitors in dance (scoring is so subjective, the number scores are so very close, and you have best friends going head to head against each other - it just has so much potential to get emotional), and IMO a comment like what Nia said was very out of line. She may have meant something totally different, but the way someone COULD have taken her comment was that Nia thinks that the people who Abby picks to do solos really aren't the best dancers. So someone who is frequently picked to do solos (which is basically anyone BUT Nia) hears that and takes it as Nia doesn't think I am a good dancer and that Abby is picking me to do solos for other reasons than my dance ability. It's just the kind of remark that can linger around in the back of those girls and mothers' heads for a long time and lead to future drama.
What Nia said would be the equivalent of a cheerleader saying "you know the coach doesn't always pick the most flexible and tight in the air girls to be our flyers", or "you know that it's not always the best tumblers that have a tumbling pass". Every flyer and person w/ a tumbling pass would really take some silent offense to a remark like that even if they didn't show it at the time.
You just don't say things like that where everyone can hear you, and especially not in the dressing room when everyone is in the middle of a performance. I was just really shocked when Nia said that.