Hello Brian, welcome to Nimble Connect.
Thanks to the Nimble Autosupport and Infosight monitoring we have the ability to monitor what features are being used and what aren't in the field. As it turns out, the Oracle DB consistency group setting was a very rarely used setting, as the majority of Oracle users much prefer to use built in Oracle tools and scripts to schedule creation and deletion of consistent database snapshots and replication. The scripts have the ability to state whether to delete or retain a certain amount of snapshots/replicas that are needed. We have sample scripts for this available - please ask your Nimble SE for these.
Therefore the ability to create Oracle DB syncronisation within the Nimble UI has been removed. I believe the documentation you reference indicates that you should select "none" as a consistency point when creating or scheduling snapshots via the UI. You can also see that the screenshots are of the older 1.4.x OS - as the documents are refreshed for 2.0 the screenshots will not show an "Oracle" option.
You make a great point about not having RBAC available within the system. Nimble OS 2.1 should make you a happy camper...!