If anything, this points out that the use case of Docker for security isolation, such as in a multi-tenant architecture, is probably still not a good one.

In most use cases I see containers used for rapid and consistent deployment. The isolation benefit with multiple containers on a host is that if you install things with different library dependencies you don't run into conflicts. As such, the comparison for the common use case is just software installed directly on the host, which also is subject to this vuln.