I disagree. If it was terrorists, what could be more terrorizing than "your flight might disappear without a trace?" It's true they didn't get a specific bargaining chip, but then again, when a bomb goes off, there's nothing to bargain with either. They do it for fame, they do it for fun.
With my admittedly limited TV info, I still suspect the pilot, who was under stress from a failed marriage (his wife had just moved out), and who was deeply upset by a political trial on the day of the flight.
Yep somehow it seems that for this to happen immediately after the verdict means that somehow it is intertwined with it -- not the only reason -- but the precipitating one.