Never let the facts get in the way of a good story, eh?
However the reality isn't very much nicer than the Express' own claims, inaccurate as they are. We may snigger at the Walloons and point out how it exemplifies the drawbacks of 28 different nation states being unable to reach any trade deal with a third party until they all agree, but that, for better or worse, is how it is because the Belgian constitution says so. If the ECJ starts ruling that national constitutions are at odds with the EU treaties, then we really are on our way down the rabbit hole.