I think this should be counted as an exhibition = not real tennis.
But still nice to see Koning win it, if you look at his results/schedule he seems to be a hard worker.
You can be sure that the Dutch Championships are taken a lot more seriously than any other exhibition match. Of course they don't count towards ranking points, but this is not just some fun end-of-season event. Players practise hard and want to win.
Koning's win here is not all that surprising, seeing as he had a good season, and the surface suits him the most of all players (De Bakker, Middelkoop play better on clay; Huta Galung on slower indoor surfaces). He also played a fair number of tie-breaks, which was to be expected.