Google does not have the right to avoid being regulated in the public interest.
It's one thing to talk about anti-trust. It's a completely different thing when you're on the same team as the government that would be bringing the case against you.
If anti-trust is your concern, make Google smaller. Regulate what % of marketshare they are allowed to control. Don't allow them to purchase any more competitors. Do things that are actual anti-trust prevention. Saying that the solution is to regulate all these little edge cases is ineffective and inefficient, because you need a different regulation for each concern that are all rooted in the same sentiment: Google is too big.
This is one method, but the massive natural monopoly over search and 'gateway to the Internet' isn't something that is particularly well served by market competition, as we can see here. If we break up google, another monopoly will develop. If we prevent monopolies from developing through strict marketshare percentages, companies will hover at the brink of these %s and lobby and bribe politicians to remove the rules. Which is what they have just done in other media markets, recently. So long as you allow the organizations to be driven by private profit, you will have to struggle against the natural market impulse for every company to exert absolute dictatorial control over as much as possible and expand its power, every moment, every year, every election, at all costs.
You should address the root of the problem (capitalism) not all the little symptoms. Require that companies that provide these public goods be run democratically, transparently by their workers as a public co-op. Nationalize them and make them all open source. There are other solutions.
In addition to everything else wrong with this, what do you do when the workers decide that your niche interest is terrible, horrible, and shouldn't ought to be available to anyone at all?
Using a competing product isn't an option because, in your world, there would be no competition, just the state-owned product and nothing.
Only this time, companies will be lobbying the employees to vote certain ways on issues which could affect search ranking and so on.
How? Because this...
> Don't allow them to purchase any more competitors.
...doesn't achieve that end.
Google could have a thousand competitors and 99% of the marketshare, because just because a competitor exists doesn't compel, or even slightly persuade, anyone to use it.
I'm all for antitrust laws. I just don't see how the usual remedies would work here.
There are also plenty of cases where regulations have greatly improved outcomes by curbing capitalistic eventualities.
I'm personally conflicted about this particular case, and have no idea which will result in a "better" outcome when choosing between non-regulastion and regulation.
However, I strongly believe that limiting Google's overall power is a better solution than regulating particular ways that Google could abuse their power, as I think the former is a better route if regulation is the route you choose.