This is not a matter of debate, whether she can or not wear the such dress. It is obivious and must for her to go with the laws of islam. Irrespective she declined herself to be a muslim.
However, it is widely believed that under muslim community womens are downtrodden and living a secondary life. But dear readers, please be informed that islam is the only and first religion giving womens their complete rights with certain limitations. If you feel that liberlism will give women a satisfactory life, it is completely wrong. Infact because of this so called liberal and modernism, you find the high rate of crime.... concerning to women is happening. Womens are to be respected and treated with love and care, irrespective of the relations you hold. They are tender and needs to be taken care with their guardians. I am sure majority of people enjoy their external beauty rather than appreciating her sports ability. I do respect her as a female, but obiviously not accept what she is upto. I am definately no one to put my thoughts on her, but i do pray she comes back to right path. This wordly success is temporary and for a short time. may allah show her right path.