It is not possible to read domain-model through unsecured management interface[1] when using Simple provider. As this worked in previous releases I would expect this to do so even after introduction of RBAC.

Removing security realm and accessing the interface leads to IAE

ERROR [org.jboss.as.controller.management-operation] (XNIO-1 task-7) JBAS014612: Operation ("whoami") failed - address: ([]): java.lang.IllegalArgumentException: newValue is null

...

[1] removing "security-realm" attribute, thus disabling authentication for given interface.