Thought about that too. From the randonauts.com website:

“If the Universe was 100% simulated, quantum-randomness could not defeat simulation. Not if every quantum-event is simulated. So there’s basically no point thinking down that route.

If everything is 100% simulated, it can’t be defeated. On the other hand… for an illusion to exist some consciousness has to be experiencing the illusion. Free-will has to exist for illusions to exist. So that leaves a few cases: Does simulation explain 10% or 90% or even 0% of what we can see?”