A process owned by any user will be able to exploit a userspace vulnerability, whatever this user is. Selinux, chroot, cgroups/containerization add a layer of protection to this, but any vulnerability that bypass these will be as exploitable from nobody as from any other local user. It will protect a user files from some access attempts but will fail to prevent any serious attack. And as usual when it comes to security, a false sense of security is worse than no security at all.

Remember that some exploits exist that can climb outside of a full-blown virtual machine to the virtualisation host, finding a user escalation vulnerability is even more likely.

The only real protection is an up-to-date system, sane user behavior and maybe a little bit of paranoia.