How do yuo know the person wasn't punishe dif in fact they were intentionally feeding, did Riot send you a message saying he wasn't punished? You also weren't punsihed for just that one instance of toxicity or just calling out soemone you accused of intentionally feeding sicne we all know that's not the truth.
The answer is still no, if it was so important to you then you'd not have abused your chat privledges in the 1st palce and Riot isn't going to remove it either as they've stated previously. If you want it gone then you have to behave and play through it. In the future you can just tell your team in champ sleect you're muting them all and only use all chat when your restirctions are up.