This isn't just about the law in the Netherlands. You have international law too. In the form of treaties, but also in the form of customary law. I know that wasn't your point, but (dis)respect does play a big role in diplomatic relations. Not allowing a foreign minister to land on your territory is a big deal. I'm not picking sides here, don't know enough about the situation at all, but I can see why Turkey would not be happy about this.
