Hi Charlie,
OpenSAP is definitely a great resource (I personally took a couple of the courses myself), and might be a good placeholder for an SAP Security Training, however it is a location that provides customers and partners with the right knowledge about the latest technologies from SAP, such as Cloud, S/4HANA, Fiori and Mobile among others, so it serves as an enabler of new technologies and platforms.
It would be great though, to see such a category in the OpenSAP application, but as for SAP Security, you need very specialized contents, knowledge and instructors. I can point you you to some of the resources that could be helpful around SAP Cyber Security:
Research Materials:
SAP Research, Publications, Advisories and More | Onapsis
SAP Trainings:
Cyber Security Training for Business Critical Applications | Onapsis
Technical Blog:
Kind Regards,
JP