Is that really the world we want, though? If Google is liable for third-party defamation, aren't they likely to deindex any negative news about anyone who threatens to sue them?
If it's about a public figure (even a limited-purpose public figure), there's no problem because that speech is already highly protected against libel claims.
If it's basically just non-newsworthy information about private citizens, then I do not think they should be shielded from liability.