How? By selling the position of preferred model? They can do that without implementing it in a way that means people who don't want it at all have to jump through hoops to opt-out.

Being able to turn AI summaries and such off by default was the final reason I started paying for Kagi. I know they use ML in the background no matter what, but as long as I get links to resources relevant to my search, that I can read/judge/summerise as needed, first and foremost, how they produce that list is not the issue.