I think it would be inappropriate to change the behavior for existing applications with regard to the ok-as-delegate flag. Allowing the realm to override and prevent delegation would violate the software engineering principle of designing for your user. However adding a new mechanism in the krb5 library and in the GSS-API so that an application can say "Please delegate if the local realm thinks it is a good idea," is a reasonable goal. It would require a new GSS flag and new APIs at the krb5 layer.