I did refer and obtain direction on your enquiry. I have been advised that NSRP has already issued the guidance that it can about asking about vaccination status and Phase 5, that it would refer you to.
Please refer to the below publication from NSRP:
https://www.ns-rp.ca/downloads/COVID_Reopening_Phase_5.pdf
Proof of vaccination is not a default requirement to access health services. Like many issues relating to the practice of psychology, ethical considerations are present. However, If a private practice / organization wants to set and implement a vaccine enforcement policy that all clients and staff must be vaccinated, it should consult with a lawyer to ensure that all human rights issues are taken into consideration and what alternatives it must consider. Other steps are suggested in the referenced NSRP publication that comprise alternatives that a practice may consider.
If a practice discovers a client is not vaccinated, then the practice would need to refer to its own vaccination policy that it has established.