Legally, an employer may require independent contractor's to wear Reebok. (a related tangent)I don't think she has to be. UFC cut them because they commanded high salaries but utilized a style that didn't draw as well as they wanted. When they got the chance to get rid they did.
That's what I don't like about the whole UFC fighters are independent contractor bullshit. If that's the case they should have just as much right to end the contract as the UFC does.
The idiots going around saying only employees may wear uniforms, that's BS. It's a contractual matter.
If the contract calls for specific attire, and both parties agree - done deal.
Legal Consequences of Requiring Independent Contractors to Wear Uniforms