ESL Duo Partner got 14 day suspended after being bombarded by slurs

So today my duo partner and I decided we'd indulge ourselves in some ranked League of Legends gameplay. I only recently hit gold, and was excited to hopefully have a change of pace with regards to my gameplay. As per usual, I link a discord server in the player chat so that I can have superior communication throughout the game with my teammates. Our ADC Kai'Sa and support Leona join. At first everything was fine, until my duo partner made a risky play, and it went poorly. Leona and Kai'Sa began to call him a "r%%%%%ed spic" and that he should "kys" I quickly removed them from our discord, and my duo partner asked what "kys" means. I just explained that it was rude without going into details and that we should just ignore them. Throughout the game, both Leona and Kai'sa constantly harassed my duo partner as well as our top laner. Finally as my duo partner was snowballing a lead, he fired back with a "kys" in chat. Later, he successfully fought four members of their team, coming out both alive and with a kill. During that fight, the ADC and support were recalling directly beside him, purposely avoiding the fight for clearly toxic reasons. This is gold after all, and I'm willing to bet anything that gold level players do not continue to recall as Leona and Kai'Sa with Leona ultimate up and Veigar hits a 4 man stun. Long story short, he then called them "fucking assholes" for leaving him. Earlier on in the game, he'd politely asked Leona to "wait until you ult please" and had kept his composure throughout the game. Basically what I'm here thinking about now is how exactly the Tribunal system allows people who display clearly intentionally toxic behavior (such as both players recalling instead of helping their teammate) to continue their pattern while my duo partner now can't enjoy their game because of the company instead of the players. Thanks for reading, would appreciate any feedback available.