Does saying "KYS" also trigger an instant ban if it's been said in the post game lobby chat?

Hi, just curious about the title, have had a friend who almost never plays league banned for this instantly after the game. Literally straight after, no wait. And today someone said it to me in a ranked game in post game chat, I reported that individual but I didn't get an instant feedback report. with the message he wrote copied pasted into the description. I'm under the impression that instant feedback report is given to players who were the latest in reporting that individual. (which would be me) Yet I still haven't gotten it and it's been a while now. Is it possible that you can say whatever you want in post game lobby and it won't be flagged? even things such as "kys" ? Also, if there is a Rioter or a mod or someone I can talk to, to tell them which player it was(for them to verify) then please, let me know where :) Edit: I just refreshed his and it appears hes played more games after telling me to KYS. Just wow. Looks like post game chat doesn't get flagged if you've said nothing/not much in game.
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