MySQL Cluster is an open-source distributed database that about half of the world's mobile network operators use to manage and route calls (it's the DB for home location registries). It is also an in-memory distributed database. And it is owned by Oracle. And if it crashes, mobile networks can go down - and with it, much of society....

This person is talking about durability and integrity of data—“safety” as it pertains to data loss and lost profits. They’re not talking about data leaks.

Elastic databases have been the source of leaks because of incompetency of the people deploying it, not because of its FOSS license.