Hint. Its not necessarily the ISC(2) writing these exam questions but members of the ISC(2). Every couple of years we have the opportunity to come together for a few days and write exam questions in a workshop type environment which has been "reported" to be a great deal of fun. Not naming names but you get the idea.
Everyone has a different take on questions and where to start. I wouldn't necessarily look to NIST but being well regarded, could certainly see no argument to doing so.