Sorry, your English isn't always quite clear.
You're saying that they will have to create that security layer that you call API, before releasing a modified Siri AI in the EU. Right? Which means that you don't see either what Apple could have done to roll this out now in the EU.

Apple seems to think that they have made Siri AI safe enough. We'll see if that is true. Apple is sure taking a risk here.
If Siri AI is not safe, then the idea to make third party assistants safer would not work either (by the sound of it).