is null value equivalent to anonymous user?

I use CCK User Reference Access to add "editors" to my node. This gives them the ability to edit the node. I then add Workflow fields to control view and edit access to my fields. This works appropriately, when a user has been added to my "editors" user reference field.

When a node is created with no user entered into the user reference field, CCK still automatically adds a row to the database with a NULL value, rather than just ignoring it entirely. I don't agree with this, but after searching the CCK forums it appears this is a conscious decision, not a bug. CCK User Reference Access doesn't recognize this NULL value as having edit ability to the node, which is correct, so the "edit" tab doesn't appear for anonymous users and this much works appropriately.

However, the fields that should have been hidden to the anonymous user are now visible because of this NULL value in the "editors" role. When I remove that entry in the database, the fields are hidden as appropriate.

Is this a bug or intentional in the way Workflow Fields operates? If intentional, can you offer any suggestions for working around it?