ExactlyWith only 12 unit sales on offer, it's not exactly a big contract. It wouldn't be hard for a complicated bid process to eat in to any potential profit, especially if customisation was required.
Given they arren't even guaranteed to win, it's not too shocking a company just might not want to risk the time and money...
KMW are offering new build Dutch machines, presumably the DMO would be asking for considerable customisation to suit ADF needs. If there are intellectual property issues regarding this customisation, that can have considerable long term financial impact.
It wasn't that long ago that the ADF turned down discounted surplus Dutch units.