In other words, people are not willing to pay enough money for the service DuckDuckGo provides to afford a spot on the list, and also DuckDuckGo's service is unable to attract as many users as they would like without the aid of the list.
I'm generally very sympathetic to anti-trust measures, but this strikes me as a situation where DuckDuckGo needs to stand on its own two feet. If your position is that privacy is more valuable to consumers, then you should compete in the auction. If your position is that it's not about the money, and privacy is an inherent good even if it can't compete monetarily, then you should be able to attract and retain your users without free advertising. But if your position is that your product cannot compete monetarily and also cannot compete without the advertising that money buys, then it might just be that you don't have as desirable a product as you think you do.
I'm generally very sympathetic to anti-trust measures, but this strikes me as a situation where DuckDuckGo needs to stand on its own two feet. If your position is that privacy is more valuable to consumers, then you should compete in the auction. If your position is that it's not about the money, and privacy is an inherent good even if it can't compete monetarily, then you should be able to attract and retain your users without free advertising. But if your position is that your product cannot compete monetarily and also cannot compete without the advertising that money buys, then it might just be that you don't have as desirable a product as you think you do.