What if your Employer Doesn't Like Your Appearance?

What do you think of the restaurant owner who laid-off a server because she showed up for work bald?   She was bald because she had sold her hair as part of a cancer campaign.  Should an employer be able to decide how an employee wears her hair (or doesn’t, as the case may be)?  Well, in unionized settings, there is a decent amount of arbitration case law dealing with this issue.  In a nutshell, arbitrators have required employers to show some legitimate business interest why the employee’s hairstyle (or piercing, or facial hair, etc)  needs to be controlled by the employer.  Usually, this means showing some evidence that there is a safety risk or that customers will be turned off or offended.  But there must be evidence of customer concern; it is not enough that the employer thinks customers won’t like it.
Sometimes, the employer’s appearance rules will also run into problems with human rights legislation.  Can you think of an example of how an appearance rule might amount to discrimination on the basis of a protected grounds in human rights legislation (see section 5, 7 of the Ontario Human Rights Code)?
This woman is presumably non-union.  Can you think of a human rights argument she could make?   Would it matter that men presumably can be bald and work in a restaurant?  I suspect this matter will resolve itself through pressure from the community on the employer to be more sensitive to a woman who has done a good thing for that community.  Sometimes the law is not the answer …