From a legal standpoint, whether or not the uniform was standard or special is not relevant UNLESS there was some assurance that she would not be asked to change uniforms (and I doubt she it was even contemplated or discussed). Unless the uniform was a violation of league rules, or unapproved by the league, that particular promissory issue would seem moot.
However, if under the law the team and/or league should have made religious accommodation (e.g. by permitting her to wear the standard uniform) and IF she was denied that opportunity after she requested it, then there is an issue.
Whether or not she would prevail, if she had filed a suit, is unknown. Aside from any failure to follow procedural requirements, the factors that would be considered:
- Is political or social identity messaging a significant deliverable or purpose of the team or league (e.g. is it in the mission statement or NGO application)?
- Can she perform almost all of her job duties if religious accommodation is not granted?
- Would accommodation adversely impact the workload of her co-workers?
If the answer is that accommodation could have been made, and the reason she is not selected for the team because the team/coach does not wish to accommodate, then they are guilty of discrimination.
On the three factors I mentioned, I think she would win.