The feature had been around for quite some time now.
Just check the Administration Guide and read paragraph
2.3.4 Reserve Connections for Administrators
You'll find that this is not bound to a specific user name (wouldn't make sense to bind it to SYSTEM when it is recommended to lock SYSTEM, would it?) but to the system privilege SESSION ADMIN.
So which ever user has this privilege, could use one of the reserved connections.
Looks like Tom Cenens is spot on about the importance of "mad google skills"...