Yes, I think OP is confused about what that means. Yes you need a valid passport within 6 months I believe, so they can issue the COPR. They don't care about your passport after this. Once you get your card, it is valid for 5 years.
Edit: I think I know why you think this. In the guide, they mention "permanent resident visas" expiry is issued for no longer than the passport validity. This is referring to the visa given to people from non-visa exempt countries, so they can land. It's not the actual PR status.