In as much as I know that what he did was totally wrong, I don't see anything like betrayal in this case. I don't support what he did neither did not condemn his action because his bet has no any impact on the performance of the club. He's just victimized for trying to utilize the opportunity that every gambler will like to seize too. It's the club that betrayed him for invading into his privacy to investigate his bets. Is there any agreement between the employees and the club concerning this? I guess No! He's not a player and can not influence the game but only analyze the team current form and place the bet to make extra money, perhaps he's underpay in the club.
I won't like playing bet against my team but whenever I play bet in favor of them and they lose the game, I do regret it and wish to have played against them in the first place. I mostly avoid including my club in my ticket when they are playing against a strong team that there winning is not guaranteed. My conscious will not allow me to play against my club. It's possible that the employee is not a fan of the club by the way but just a worker and he has the right to play his bet as he wish even as fan.
If your suggestion says that what he did is wrong then it's right to see it as betrayal to the club he works for, left for me I'll only see it as wrong when there are certain rules that goes against his actions if not i don't see anything bad in trying to make an extra cash by betting against his employers, if my employers are constantly performing poorly and I figure I could make extra money if I bet against them, I think I'll seize that opportunity. Also there are chances that he could've lost one of those bets cause I've seen situations where underdogs become the Victors, but in this case they kept losing so it's a plus for him. What if he had bet on them to lose and they won on more occasions would they still query him for losing his bets? no I don't think so. I'm a die hard fan of the team I support, I've never betted against them, I'll rather bet on number of goals or both teams to score or my team to win or draw but in a case where they have a poor season and keep performing poorly on a regular, I think I'll be forced to bet against them in certain matches were they're definitely the underdogs.