No one said retail workers have to work the holidays.
It is not exempting the public holiday for the employee. That is governed by the Employment Standards Act.
It is allowing the business to legally open on the holiday. The Retail Business Holidays Act.
The employer cannot legally make you work the day per ESA. You must agree to work, and accept the pay + day in lieu.
If you do not accept, you continue to receive your day off as usual. They cannot just schedule you to work that day, unless it is part of your employment contract already - in which case this thread has nothing do with you as it was already legal for the business to operate on that day.
tldr; two completely different laws for two completely different things