That's an interesting suggestion but it has nothing to do with the problem at hand.
The problem here was a feature somewhat haphazardly added to Rails for ActiveResource was turned on-by-default and enabled features that should only be active for interactions with trusted clients (i.e. authenticated services running in your own infrastructure)
Your suggestion is not without merit, but this is a case of having to learn to walk before you learn to run. There are clearly much more egregious parameter parsing vulnerabilities which need to be solved before the things you're describing would ever make it into rails-core.