It doesn't punish players enough to make them not leave roulette choices they don't like. People are sick of queuing for roulettes just to have someone leave right away. And I understand things come up in real life suddenly and leaving is unavoidable.
Personally 30 minutes is nothing. I could go gather for 30 minutes, it wouldn't be a very big penalty for me.
Could you change the penalty to, say..
"Cannot enter a roulette for 3 hours."
OR even make their future roulette bonus for that specific roulette be cut in half? idk