Now such list view has action "Delete" but doesn't have action "New". Why? I think it is better to remove action "Delete" too, because sometimes one presses it instead of "Unlink", and people usually create and delete such linked objects in their own views.
See Also:
SystemModules.Link - the AllowNew and AllowDelete attributes for nested ListView should not impact the Link and Unlink actions
We have closed this ticket because another page addresses its subject:
SystemModules.Delete - Provide the capability to deny the Delete operation for some collection property