Page 92 of NOM Admin Guide says this.
"NOM, as opposed to NBU, does not support role-based access."
After that, it then mentions admin type user and non-admin type user, but that's not about restrictions on what NOM user can see and do.
Then on pages 92-93, it says this.
"Normal users of NOM can perform all functions (for example, NetBackup monitoring, management, and reporting), except the management of other NOM users."
Which to me sounds like "a NOM user, whoever it is, can see/monitor everything about NetBackup master server and there is no way to give restrictions on what to see"
So, I think the short answer to your question is no.
This guide can be downloaded from
ftp://exftpp.symantec.com/pub/support/products/NetBackup_Enterprise_Server/290227.pdf
Cheers,
Abe