remove confusing attempt at clarification

Author: phryneas

rfcs/ObjectIdentification.md

@@ -16,7 +16,7 @@ Also, the Global Object Identification pattern is not enough for the use case of
 
 This proposal introduces a new introspection field `__id`, which can be queried on any object, interface or union type.
 The field is of type `ID` and for each individual type, the field must either always return a non-null value or always return null.
-It might never be `null` for some objects of a type while being `ID!` for other objects of the same type. 
+
 If an `__id` field returns a non-null value for a type, this value must be guaranteed to uniquely identify the object when combined with the value of the `__typename` field.
 
 This would allow clients without schema knowledge to query for `__id` on selection set and use the returned value for caching or referencing the object in other systems, if it is not `null`.