To me, there is different layers to gambling.
Rose was managing so he had a direct influence on lineups and games. So he could swing money lines, spreads etc...
Correct me if I'm wrong but Ridley was betting on games that involved his team but not him. So presumably money line, over/under, spread, stuff like that. He had no control on that although you can argue he had inside knowledge of stuff.
Porter seemingly was involved in some manipulation with prop bets. It's not point shaving per se but its fixing/manipulation.
So not all gambling scandals are the same. But I certainly think what Rose & Porter did was more egregious than Ridley.