This is a flawed analogy. The "keyboard manufacturer" in this scenario is the "router manufacturer" who Cloudflare buys off of, not Cloudflare.
In your scenario Cloudflare is more like a newspaper aggregator which carries all sort filth along with it's normal commentary.
If this was a normal situation one could just decide not to read some filthy newspapers, while letting those who want to read it make that decision for themselves.
But in the Cloudflare scenario all the major relevant normal newspapers decided to publish all their content through Cloudflare and if something objectionable is published along with it, instead of taking your beef to the original publisher, you have to to take it up with Cloudflare who might just forward your details to some very unsavory people without you having a chance to know beforehand.
In your scenario Cloudflare is more like a newspaper aggregator which carries all sort filth along with it's normal commentary.
If this was a normal situation one could just decide not to read some filthy newspapers, while letting those who want to read it make that decision for themselves.
But in the Cloudflare scenario all the major relevant normal newspapers decided to publish all their content through Cloudflare and if something objectionable is published along with it, instead of taking your beef to the original publisher, you have to to take it up with Cloudflare who might just forward your details to some very unsavory people without you having a chance to know beforehand.