Could be that BMIr are replacing one German route with another, and they do like German routes after all...!
I think they will only ever go for routes from BRS that can be both business and pleasure so I don't think we will see any routes like Oslo or Gothenburg from them unfortunately. Düsseldorf is a strange one for me; average sized city albeit on the Rhine. Reasonably close to Dortmund but not much else (Cologne, Essen)