The provided example fails validation because of the us-core-8 invariant.

us-core-8

Patient.name.given or Patient.name.family or both SHALL be present [family.exists() or given.exists()]

Data Absent Reason Example:

{
 "resourceType" : "Patient",
 ...
 "name":[
 "extension" : [
 "url" : "http://hl7.org/fhir/StructureDefinition/data-absent-reason",
 "valueCode" : "unknown"
 }]
 ]
 "telecom" :
 ...
 }

Proposed Resolution:

Either the invariant needs to change, or the example needs to reflect the requirements of the invariant (e.g. DAR extension on Patient.name.given or Patient.name.family).

See https://chat.fhir.org/#narrow/stream/179175-argonaut/topic/Data.20Absent.20Reason