Today I learned that SELinux can be disabled in two ways during boot. Besides
enforcing=0 there is also
selinux=0. The former will obviously set SELinux in permissive mode but still label all new files properly. While the latter will disable SELinux entirely and therefore break your system by labelling all newly created files with
default_t on next SELinux-enabled reboot.
I learned this from this talk about SELinux I watched today.