[fs.op.absolute] has a note giving strong encouragement, which should be normative:

[Note 3: Implementations are strongly encouraged to not query secondary storage, and not consider `!exists(p)` an error. — end note]

The part about `!exists(p)` not being an error could definitely be a Recommended practice paragraph. Referring to "secondary storage" might need to be phrased differently to be normative (maybe with a note clarifying that the normative wording is referring to "secondary storage").