Is it truly either-or? Obviously the root of anti-cheat needs to be totally locked down, aka the TPM. But almost all "open" computers have a locked down TPM. The TPM doesn't need to prevent you from running an unsigned firmware, kernel, modules or user software, it only needs to report on whether you are / have. You can reboot your computer into "trusted" mode and run your games with anti-cheat. Then when you're done playing you can as much unsigned software as you want.