In my head isolation and containerization are two completely different problems. If you really want "complete" isolation in plash you'd just had to setuid/setgid/setgroups away from the namespaced root user. Then as far as the kernel is concerned you would be a different user and if you are the only process with this uid you are completely isolated. Maybe I'll add an flag for that.
EDIT:
I am not happy with it at all but changed it:
- Security: Traditional per user isolation. Containers run completely unprivileged.
Containerisation and sandboxing are two different things. Sandboxing in major container software is fundamentally broken !111