The first thing you want to do is clarify whether the employee is actually requesting an accommodation and, if so, on what basis. Remember that under human rights laws, accommodations are required only for employees or job applicants that have disabilities or other personal characteristics protected from discrimination, e.g., age, sex, religion, family status, etc. Once you get clarification on this, you can proceed accordingly.
If, as I suspect, working in Ontario is just a personal preferences, you don’t have to accommodated unless the employment contract says otherwise. It sounds like precisely the opposite is true in this case. Hope that helps. Glenn