The point of TFA is that you are not letting it do whatever it wants, you are restricting it to just the subset of files and capabilities that you mount on the VM.

Sure, and right now they aren't very capable, so it's fine. But I'm interested in the mindset going forward. I've read a few stories about people handling radioactive materials at home, they usually explain the precautions they take, but still many would condemn them for the unnecessary risk. Compare it to road racing, whose advocates usually claim they pose no danger to the general public.