During local test deployment, I restricted metadata privileges to "Owners" of the metadata. However, User 1 can still edit the ingestion source created by User 2 and add himself as an "Owner" of the metadata, re-run the ingestion source and now User 1 can view/edit metadata extracted by User 2's ingestion source.
(of course this is picturing an extreme case of malicious use but I am coming from a "covering all angles" intent in order to properly present this tool to stakeholders. Thanks for understanding!)