Since this profile is constrained to use LOINC codes I think we should change Observation.value to disallow the boolean data type. All LOINC terms with a scale type of Ordinal or Nominal which allow true / false answers have their own Answer Lists with specific concept codes. For example LOINC term 80407-0 (Contamination/radiation/contagion status) is bound to preferred Answer List LL3865-4 which is a value set containing True and False concept codes. So a corresponding Observation resource should use the value type CodeableConcept. I don't think there are any LOINC terms where boolean would be a valid value type.