The GPL FAQ and even the GPL itself have only a limited freedom to redefine copyright. It starts out with copyright law, and then adds precedents set by courts. Now copyright law generally doesn't talk about linking, but it often does talk about derived works and aggregations. Judicial precedents are more detailed, but also more varied.
Having said that, the courts do admit professional fields like software development to define their own interpretations by consensus. That's why you see expert witnesses in trials. The GPL FAQ is right; the consensus in the field is that the act of linking creates a derivative work. For Python, I'd argue that there's no such clear consensus yet, but I couldn't point out a derived work. The Python interpreter is running code from multiple independent sources, but each of those sources appears to be an independent work. If anything, this would be an aggregation in legal terms, but even that's a bit of a stretch. An aggregate work is typically not as volatile as a running Python program.