1. Ad-free premium search is already an option with Brave Search, and the ads in the free leg we just launched are privacy-preserving, but none of this proves the "free and open exchange" claim. The "free" part was intended to mean no-payment-required, because many can't afford and some find ads useful. The "open" is thorny and should have been separated: all engines have biases even if algorithmic, from the Web they index if not how they weigh and measure inputs to their indexing.
2. Some folks do find ads useful (I do, on Google especially as its organic results have declined in quality since the old days, but even in the old days). These users will probably prefer the free leg on this basis, and that's what the last clause of this overlong sentence was trying to get across.
We will do better in future posts. I hope the privacy-preserving nature of search ads is clear too -- if not, please reply and I'll take back your feedback there too.