They are using brave search results, like they do with others. Frankly, you could build totally identical arguments (and to be honest, much more serious) for "partnering" with Google and Microsoft, but then the product wouldn't exist and wouldn't be as good.

The relationship with the Brave founder is so indirect, that this - to me - feels like an argument from someone who is looking for reasons to get angry. Kagi probably uses AWS (or other clouds), which funds Amazon (known for terrible worker rights), funds Google, fossil fuel industry, etc. It's a sad reality, but you simply can't exist nowadays in the moral and ethical way many people would like. You can, only if you are a privileged one. Technologically speaking, Google can probably do it, for example (own hardware, DCs, tech etc.). We can choose to fight those that directly support political agendas we disagree with, or we can damage the smallest players by demanding they will be 100% pure and ethical by not having any relationship with those with those agendas.

In my personal opinion, such unrealistic ethical requirements end up being a reactionary choice as they will ultimately impede new - better - players to emerge and will leave the existing - worse - dominating.