This is not anti-trust
I have no love for google, I like my privacy and I dislike being tracked. Having said that, there is no way this is anti-trust.
People use google as a search engine because... it turns up useful links in what is generally considered to be a good order. Or at least in a good enough order that it's useful to use google over any other search engine.
If people feel google is prioritising it's own search results (which it almost certainly is) and those links are irrelevant, or not what they wanted, then they certainly would use some other search engine which prioritises different links.
There is no problem of compatibility, a search engine is a search engine, it does the same thing no matter who is running it. The only difference is speed and relevance.
What it really boils down to is this: Google Search prioritises links to other google products. These products are integrated into google search (See the stocks chart without having to click on the link). If people think that the link presented isn't the most relevant one, nothing is locking them into using a google product. They CAN go elsewhere.