This is almost surely not content hosted on Google.com, but content hosted on sites which Google redirects to. If Google serves a single malicious site as a li

This is almost surely not content hosted on Google.com, but content hosted on sites which Google redirects to. If Google serves a single malicious site as a linked result (or in a redirect) it will flag Google.com as hosting malicious content. This has been the case for years now, also for other Google properties, like Youtube and DoubleClick.