Security+ is not the fifth step on the same ladder. It is a separate implementation of Solibri for organisations working in air-gapped, sovereign, or classified IT environments. Fully offline. No telemetry. No external dependencies. Named, device-bound license.
The audience is different too. Government and public sector, defence and security, intelligence operations, owners of critical infrastructure, and consultants working inside restricted environments. Procurement runs through an assessment, not through Solibri Store.
If your work cannot connect to the internet, Security+ is the path. If it can, one of the four tiers above is.