Things we know today were not necessarily known 5 or 10 years ago and 5 or 10 years from now we may have a completely different set of beliefs. Just because someone has a normoxic card, that doesn't mean that they are current and up to speed on the latest beliefs. Here's an example, if they earned that normoxic card in 2010, they may very well believe deep stops are incredibly important to avoid getting bent.
So, in answer to your question, >> I << wouldn't assume anything about their knowledge and skills based simply on having a piece of plastic, and >> I << would cover the material, including "remediation", as necessary.