Harsh and sudden permanent ban for a returning player

 I recently returned to playing LoL at the end of season 5 and for season 6.  I cannot recall a convincing record of negative behavior on my account. 

I last played a match where a teammate initiated toxic behavior, followed it by intentionally feeding, and continued flaming/surrender-spamming for the rest of the game. These games are always to hard to remain calm for the entire team. I uploaded my side of the game chat log. I have requested the full game log from Riot through Support Requests.

Excessively rude and negative behavior as far as I've understood generally contains more offensive words than childlike ones of "nerd" and "doofus." I've been led to believe excessive cursing, racism, homophobia; i.e. use of words like F*** or N*****, were less joking and more angry and mean.

I'm curious where and what the tipping point is in this chat log, which would be nicer to see full chat log since I wasn't talking to myself. Riot claims to encourage reform but have acted quite sudden with a permanent ban and I feel in the dark about exactly which part of my behavior is not welcomed.

EDIT1: There's a clear niche community here and the same silly immature behavior as in game. I talked to some people who had things to say, others didn't.

This community was once a lot more acceptable and reasonable. It is now far too sensitive and ironically points blame in the wrong direction and believes it can solve a problem it doesn't understand using naive methods that don't work.