That or he is stupid, had big hubris and thought he would get away with it just because his passport had different name on it. Since should he have gotten past Finland, he would have likely been caught in France or so on. Whomever (likely suspects would be Ukrainian or American intelligence) tipped off Finnish law enforcemen could have just as easily have later on tipped of French security services “hey this guy is in Nice, wanna go arrest a war criminal?”.