But isn't that scenario "Game Over" anyway? At least installing kernel extensions is a process that is explicit and - importantly - not just another 'trained to ignore' permissions dialog. The alternative would be to prevent the user from ever installing kernel extensions unless they turn off security, and then you are back to square one. At least this way, authorised kernel extensions are taken under protection and not just left lying around for potential modification?
My main frustruation with SIP has been with environment variables starting with LD and DYLD being silently swallowed e.g. `DYLD_SOMETHING_SOMETHING=a env | grep DYLD` gives no output. So if you want to use these variables, or have existing scripts that do, you have to know what the command you are launching is - if it's an executable bash script, then the variables will never make it in.
SIP isn't perfect, and can be frustrating, but it certainly raises the bar for compromising a whole system.