OK, so I apparently misread things in one place or another and was wrong here. OpenVPN docs can be quite detailed but they lacked some detail here that could have made things much more clear.
The OpenVPN 2.4 client installs a service, OpenVPNServiceInteractive ("OpenVPN Interactive Service") and sets it to run.
As long as that service is running, the OpenVPN 2.4 GUI will talk to the service and it does not require Admin privileges.
So the manager is no longer needed, it seems. More testing would be appreciated.
While I am updating it for OpenVPN 2.4, I'm going to remove the manager from the OpenVPN client export package as it is no longer necessary.