Several companies are looking to provide a solution for the AI bot problem. Cloudflare stands to make a lot of money if people pick their solution. But Cloudflare backing down won't make the problem go away, and someone else's bad solution will be chosen instead.
The gatekeeping described here is gatekeeping a website owner chooses. It's an alternative to pay walls, bespoke bot detection, or some kind of ID verification. Cloudflare already provides a service, but standardising the service will open up the market (at the cost of competitors adopting Cloudflare's standard).
The freedom of the open web also extends to the owners of the websites people visit.
You could use the same argument against antitrust laws. All monopolies were "chosen" by their customers, that doesn't mean we should give them a free pass.