A reserve day can't satisfy the provisions of a CAO day off.
CAO 48.12 (my bold)
A pilot shall not commence a flight and an operator shall not roster the pilot for a flight unless during the 7 days period terminating co-incident with the termination of the flight he or she has been relieved from all duty associated with his or her employment for at least 1 continuous period embracing the hours between 10 pm and 6 am on 2 consecutive nights.
Reserve is clearly not a "tour of duty" under the orders but it is nevertheless "duty associated with his or her employment" whether you get called out or not.