League Banning System is Confusing me.

Yes, I know that my language can be a bit harsh. But really Riot? I spend a whole game pissed because in the pick ban phase a blitzcrank bans my declared champion and calls me dogshit. I still tryharded and we end up stomping the enemy team. Then I get my first 14 day suspension. ??? I check my chat logs and here is what I see

Game 1 In-Game 48602313428 : stupid ass robot bans my champ and fucks me over 48602313428 : was ur naut skating? 48602313428 : that was close 48602313428 : nice4

Like i know my words can be offensive, but I jsut started the game showing my frustration, then proceeded with the game. Why does this get me banned?