They've always had a hard-on for Kobus. He was being described as "the most dangerous guy in the Netherlands" for years and years. Now he's not a man to be fucked with, but it's not like he was putting hits out on everyone and everything.

John Wassink had quite a few nutters running around in his entourage. They chopped up a Belgian frat boy pot dealer just as a show of force. There are probably many others reasons for having Wassink killed instead of a petty fight with the daughter of Kobus.