[mullingitover]

It still boils down to a first amendment issue: can the government tell Google what it can and can't say? If Google is using its market position illegally, that's one thing, but there's no such thing as an illegal use of its free speech rights (except as legally prohibited, e.g. libel). Google could keep a 'We think Trump is a traitor' banner on every single one of their pages and be within their rights under the Constitution.