Gryz: I think pre-arranged draws are done more often. And they are "frowned upon". But not necessarily illegal. Especially when it's the last round, and somebody has to be somewhere else on that last day.
Apparently the organizers had told Tiviakov that the playing days would be a little earlier. So he thought he could have played all rounds, but miss the closing ceremony. It turned out the last round was a day later than he was told. So Tiviakov wasn't happy.
I think the organizers started to make trouble not only about the last round, but also about missing the closing ceremony. That's when Tiviakov decided to just drop out of the tournament.
Small detail: that happened after round 3. At the start of the tournament, Tiviakov was the expected winner. But after 3 rounds, he had 1-1-1, and his tournament win was suddenly a lot less certain. I'm sure that had an influence on the decision making of Tiviakov.
Anyway, my personal opinion is this:
If players are unhappy with the amount of prize-money or start-money offered at a tournament, they have every right to refuse to play. If the tournament is the Dutch Open. Or any foreign tournament. Or even Wijk Aan Zee. But if it's the Dutch Championship, I think they have some moral obligation to show up. Just for the honour. Just for their fans. Just to keep our national championship at a certain level. Even if you're a professional, that doesn't mean you do things only for money.
It all started with Timman. He refused to come to the Dutch Championships for years. And now he wonders why he's not popular with the Dutch chessfans.q