There is no bias against the Dutch per se, it's just that they are all very young, and I think it's also pretty normal in Dutch culture to be fairly direct (not rude, but to be simply straight talking). This means that they are often less politic than others (this is NOT a criticism - I admire honesty). They are also easily identifiable, so making it more obvious how they are treated.
As for the English FO passed over because they didn't go into discretion, well the captain and the FO were to be disciplined, but BALPA managed to stop it. The FO was used as an example to other FOs who might not do as they were told.