If you "violate" a robots.txt the server administrator can choose to block your bot (if they can fingerprint it) or IP (if its static).
With an ai.txt there is no potential downside to violating it - unless we get new legislation enforcing its legal standing. The nature of ML models is that it's opaque what content exactly it's trained on, there is no obvious retaliation or retribution.
I don't think that's what OP is envisioning based on their post!
The purpose OP is suggesting in the submission is the opposite, help AI crawlers to understand what the page/website is about without actually having to infer the purpose from the content itself.
I don't see the OP saying anything about "ai.txt" being for that? They're advocating it as a way that AIs could use fewer tokens to understand what a site is about.
(Which I also don't think is a good idea, since we already have lots of ways of including structured metadata in pages, but the main problem is not that crawlers would ignore it.)
In other words, there's no need to create an ai.txt when the robots.txt standard can just be extended.