he's not saying it's impossible to figure out some piece of code, but "all" code. There is just too much of it! Going into even something as relatively simple as an operating system, let alone a whole ecosystem with drivers, internet protocols & more would take many lifetimes.
The "anyone" part comes because there are countless parts of those infinately complex systems that have no documentation and no maintainers. They can individually be reverse engineered if it is needed in an individual case, but nobody is going to do that for most of them.
The "anyone" part comes because there are countless parts of those infinately complex systems that have no documentation and no maintainers. They can individually be reverse engineered if it is needed in an individual case, but nobody is going to do that for most of them.