Simply because you were banned doesn't mean the person you reported wasn't.
From a complete spoon to the bad section of a community, player and moderation continues to be spammed by the same message:
>WHY DID I GET A BAN WHEN THE PERSON I ABUSED AND HARASSED, THESE PEOPLE DONT DESERVE TO BE FREE GG EZ!
Well guess what, your ban happens regardless if they're banned or not, reports aren't some black and white case where one person gets punished and the other gets rewarded, just as two arsons get fined regardless of who set who's house on fire first.
Stop assuming your ban wasn't justified because it's retaliation. Retaliation is unacceptable regardless of context in LoL and even in laws and society. You have every bit responsibility to take for talking back and telling someone something that was better left unsaid.
TL;DR: you say it, you get banned, don't you even dare bring up who you said it to.