Luke,
Exclusions of capabilities can't be done in the 7-mode versions of ONTAP.
You're not the only one who has asked for it
There are business sectors and environments where roles need to be carefully defined and not having the ability exclude has led to the creation of some very cumbersome Role Based Access Control policies.
If c-mode uses the same style command tree as GX did, exclusions will be possible.
No help for you right now of course but a potential light at the end of the tunnel perhaps!
Richard