I'm not particularly surprised to see Turkulainen being left out of the team. Tiny finesse players quite often struggle to make a difference at World Juniors, just think about last year and how insignificant Petrus Palmu was despite performing very well in the OHL.
It's necessary to have some bottom-6 forwards that perform well in short handed situations, so that the team can spread the workload in a tight schedule like the World Juniors. It's worth noting that Turkulainen doesn't have much experience from playing on the penalty kill if we look at the recent history. Last season Turkulainen played 48 regular season games in Liiga and received 61 seconds of ice time during short handed situations. This season Turkulainen has played 29 regular season games in Liiga and has recieved 43 seconds of ice time during short handed situations.
Another thing that came to mind is that Turkulainen has only 1 point from his last 9 Liiga games, he isn't necessarily the hottest player right now. Admittedly he's done better in Champions Hockey League, but nonetheless he hasn't been the most consistent offensive producer as of late.