Hi ZuckerRat and welcome to TheSinclairMethod!
Yes, it seems that when you use insurance, info like that gets through the health system. Some professions won't allow those that have been on such meds and life insurance rates can be higher as well.
The only way to avoid that is to use a private physician and pay cash for your prescription, or to order from overseas. I don't know of any overseas pharmacies that will ship to Canada, but All Day Chemist will ship to a US address if you can send it to a friend or a US PO box. River Pharmacy (based in Canada) will ship to a Canadian address, but you have to finish the order over the phone. Neither requires a prescription.
Otherwise, there are Canadian TSM docs on the "Find a Physician" list, under International Verified and Telemedicine Providers:
http://www.cthreefoundation.org/find-a-physician.htmlIn any case, unless you can ship to a US address, Naltrexone is rather expensive in Canada ($6-10 per pill) with a prescription and no insurance.