the next step is to debate what is AI and what’s not.

Unnecessary, in my view. If you use a tool to produce something, and that something breaks a law, then you are liable, not the tool. Doesn't matter whether it's a hammer or an AI. If a human employed by Google had written the incorrect summary on Google's behalf, then Google would still be liable (the difference is that the human writer might also be individually liable, depending on local law).

Search engines received various kinds of legal immunity in many jurisdictions because they were only presenting information written by third parties outside their control. These summaries are not third-party content, and if they are libelous, the responsibility falls squarely on Google.