The bit about modifying the Linux code is to say you can't run a a built-from-source version of the kernel or DE, like you could do with Fedora or Ubuntu or Arch or distro.
The bit about "now more than ever" is because by separating the browser and OS (Lacros) it's no longer the browser-based OS we've always known it to be. Now it's Google Linux with Chrome browser (Linux And Chrome OS).