Just that in those unknown unknowns lurk many more memory safety issues, that we have not yet discovered and the longer we continue to run that code, the more l

Just that in those unknown unknowns lurk many more memory safety issues, that we have not yet discovered and the longer we continue to run that code, the more likely we will some day get hurt by them. Also we don't know anything about safe code, until we have proven it to be safe, either mathematically (difficult!) or by proving a type system sound and using that for implementing things.