Most of that "public data from the Internet" is subject to licenses, yet their entire business model is built on top of a legally grey algorithm that ingests that licensed code and spits it back out without the license. They have no legal right to any of that code, they're just getting away with it because laws are for the poor.

If you believe any data that is publicly accessible is fair game regardless of licenses, then by that definition, Claude Code's source code is included.