An anti-cheat relying on a kernel module would have to provide the source code of that module (the glue part, at least). One could then modify and compile that module as he want. Also, you could easily write a sandbox environment at the kernel level dedicated to a specific anti-cheat.
This smacks of "security through obscurity" to me. Windows has been thoroughly reverse-engineered by black-, gray- and white-hats: is there a single windows .dll, .sys or other component whose purpose is remains a mystery or cannot be subverted by a person with physical access?
It is. Any anti-cheat system that relies on having explicit control of the client is inherently flawed, but it is considered "good enough" by most people.
