Then maybe we can also take into account whether the emulated input comes from remotely attested assistive technology. Yes, this will have the effect of at least restricting third-party assistive technology, but we have to keep in mind what's best for the largest number of people (including disabled people who aren't hackers) in the big picture, rather than taking an absolutist stance on hacker freedom.

That makes the tech far more expensive because you introduced useless overhead without gaining anything relevant.

You didn't protect non-tech savvy users at all, on the contrary, you introduced a point of failure for their devices. Some have customized ones which would need to be verified. Doesn't sound like a good idea at all.

Again, it's all chainable. If an app is being controlled by accessibility software, the identity of that software can show up in the RA, so readers can say "it's OK if this app is automated as long as it's by something on this community maintained list of genuine accessibility tools".