@HebrideanHecate @Flick @FeartnTired This is very similar to Chomsky's demonstration about how syntax isn't dependent on semantics, i.e. you can have a semantically nonsensical sentence which is nevertheless grammatically perfectly correct. It's basically an illustration of the difference between syntax and semantics. He was also making a point about how probabilistic grammar analyses are inadequate when it comes to explaining whether highly unlikely sentences are grammatical or not, but that's a very geeky side point.
His was colourless green ideas sleep furiously.
Politically Chomsky's a right weirdo, but as a linguist he was not without contributions. Although his TG grammar has since been determined to be of much more limited utility than originally thought.