He should hope that they remain in Syria.
He should be, if they unfortunately make it back to the Netherlands, they bring with them deadly new skills, and they will one day, put them to use. The jihad doesn’t end at Syria’s door, they have the whole of Europe to deal with as well.
H/T: BadNewsFromTheNetherlands:
He is worried that they will return with fighting experience and then can present risks to the Netherlands. He added that “this isn’t so in most cases.”