They interviewed him on NPR this morning, He sounded firm and fairly reasonable, wanted to deport any and all criminals and enemies of democracy. Also talked a bit about restricting immigration, but quickly turned that into support for socialism, giving jobs to Muslims already in the Netherlands, free education, etc.
His thinking apparantly (besides being steeped in socialism) is that integration, assimilation and social programs will prevent radicalism. But my view is that the emptiness of cradle-to-grave socialist life will just give them 5 or 6 weeks vacation plus religious holidays to study jihad.