Maintenance mode == root

You're projecting your meaning of it, not mine. Not if it can't be undone in a way other than reinstalling everything. A mode that allows changing things with a temporary reduction of security system-wide and restoring them later, but putting all of the upgrade and support liability on the user without sacrificing functionality. Think VMware ESXi. If tech support wants to not support it, that's fine, but payments and such should still work.