I don't think any assumption was made here. It is as much an assumption to say that all information necessary and sufficient to decode grammar into its constitu

I don't think any assumption was made here. It is as much an assumption to say that all information necessary and sufficient to decode grammar into its constituents is not detectable from spoken words that a child is exposed to. That's a theoretical argument. Just because we can't think of a way this could be done, doesn't mean it can't be done. At the moment, we simply don't know. I think what the comment you're responding to meant is that this study shows no evidence for an innate internal language or grammar, which I thought was Chomsky's most controversial claim.