With four yellow cards for minor offences within 30 minutes, it looked as if referee Hrinak likes to start a match by making a couple of booking regardless the foul committed just to show his strength. During the rest of the match however, fouls were as often allowed as not.
So maybe his rules weren't clear, but Swiss Hodzic's elbow in Ajax midfielder Schneijder's face was as intended as any shot on goal and Vladimir Hrinak should have seen it. And since he didn't (players know a referee won't see an offence because he often turnes his back to follow the game), his assistant should have seen it. The Slovak assistant wasn't up to it.
There is a rule in football that states that when an attacking player who moves towards the goal with no defenders between him and the goalkeeper, is tackled (with the object to let him fall), the offender gets sent away. This is not a very difficult rule, neither is it ambiguous. The facts are easy to see by everyone: there's the player, there's the keeper. For everyone but Hrinak who might have been a little careful about sending off a home team player. The player in question, FC Thun's Ferreira got a booking. Actually by acknowledging the foul Hrinak couldn't do anything but send him off. You show a red card or you do nothing, a yellow is not a possibility.