Situation 1: You want to advertise your product or service. There are endless options outside of Google, including some options where the audience is counted in the hundreds of millions.

Situation 2: You want to let others advertise their products or service in your space. There is an endless amount of companies which you can contact to make advertising deals. If you are too lazy to do that and want a third party to take care of it, then you can use Google as a middle man. But they are not obliged to do business with you.

If the justice wants to go after Google, then they could (and should) prosecute Google (and Meta, and Twitter) for all the scam and malware ads they permit through their platform. That is billions of dollars of money laundering, and the CEOs should be imprisoned for this. For life.