You are not running uniformly random instructions on the CPU. It doesn't matter how many 9s there are in that percentage, if an attacker knows that 0.000...01%

You are not running uniformly random instructions on the CPU. It doesn't matter how many 9s there are in that percentage, if an attacker knows that 0.000...01% code, you have a problem. It actually makes it more insidious, since the chance that is occurs accidentally is basically zero (unlike previous CPU bugs).