I wonder if this could just be controlled with a feature flag and tune2fs and/or a mount option? When set, just disallow creating files which have the troublesome characters. Still allow access to existing files with the troublesome characters, though, so you never have "files you can't get to."
Invariably, whenever I've created filenames with control characters in them, it's been through some strange fat-fingering. I would rather have the OS throw those files away. :-)