14 Day Suspension

So I was recently given a 14 day suspension, and the given reason was this as the chat log (copied from the link given upon log-in to the client)

Game 1 Skrubbythethird: Kindly report yi... before game even starts calls me a %%% and %%%%%% hahahah Skrubbythethird: I called and locked in my lane Skrubbythethird: Negative shipmate. Skrubbythethird: What tipped ya off lol Skrubbythethird: or not lawl Skrubbythethird: 1337 skillz Skrubbythethird: Does sion still have infinite health potential? Skrubbythethird: Still on the W? Skrubbythethird: #allthehealth Skrubbythethird: Lol #rood Skrubbythethird: I'd like to as well Skrubbythethird: Bai bai Skrubbythethird: Lol gg Skrubbythethird: Twas fun

I locked in before I'd seen said player had said anything in chat, and I had put my own intentions in the dialogue, and immediately was set upon by him. I felt no need to defend myself or attempt to de-escalate the situation, and yes, had a bad game (tried to invade in order to recoup lost gold from splitting jungle, went downhill from there). I muted the player in question a few minutes into the game, and don't understand how this puts me on a suspension.

Edit: while I didn't attempt to de-escalate, neiher did I escalate in pre-game chat.