If this is an argument against trusting the Linux's specific current implementation of OS-level containerization/resource-limiting, I can buy that. But I don't think full virtualization is the only or best answer. Solaris Zones (and their derivatives via OpenSolaris/Illumos) are a pretty solid implementation of the concept that has a good security record with quite a bit of production use. FreeBSD jails are also pretty solid nowadays, though they used to be somewhat buggy.
Another example is OpenVZ, which offers an alternative to lxc for Linux. It requires patching the kernel, but is considered solid enough that multiple VPS providers actually use OpenVZ under the hood.
Note: there will probably be an OpenVZ backend available for Docker at some point :)
