They aren't looking for the Rootkit though (Score 1)

"The crux of the matter is that a perfect emulator of any sufficiently complex system would have to be a bug-free program, and we don't know how to write those yet,"

Compare this to making a "secure" operating system - every bug doesn't have to be secured - just the ones that are being exploited. Same with anti-virus programs - they don't catch all viruses, only what they know to look for.

So the rootkit doesn't have to be perfect to be invisible to *most* users... it just has to hide from the AV software (or other security). And as the security software gets better... so can the rootkit, ie, in the next "version" add the bugs that the security programs are looking for.