It would be very useful to have a local Belgian rider/kite flier clear up the story for us. First hand what is really going on? How did it happened to come to this ruling?
Other thing Belgium is the Rules and Laws center of EU. Every office worker burocrats does know and read the paper. Even if say the ruling was necessary for that local coast line, those office workers might get the wrong idea and if for nothing else to justify their job will propose and push through similar rulings around the EU. That would be a shame.
my 2 cents

It's been coming a long time ... they had a couple deaths and this seems to be the reaction