Should we also ask if Google is competing in TV production business, luxury watch bands, or computer wheels ?

To get back to the original point, Apple has a browser, and the means to raise a case against Google being too dominant in the browser space. They'd have plenty evidence of Google interfering with the market if they'd go all in and were faced with unfair practices. They never did and probably don't intend to, because they kinda don't care as long as Google isn't threatening their walled garden.

That's where the "Apple is the only defense against V8" falls flat to me.