I just went afk in a ranked game. Hear me out.

I just went AFK in a 2000 elo solo queue game. I was first pick and picked malph mid. All the picks went fine untill the last person dicided he'd like to go mid as well and picked tf. He said something in french about not wanting to support and the game started.

In the game, I explained to him that i announced about 3x that i was gonna mid with malph and that he should go top. He went to my lane and took my creeps. I went afk then because I couldn't stand him.

Having done this, I feel a bit guilty. I know it's wrong towards the other 3 (8) players but something in me also says that giving in to people like this makes makes the game worse in the long run. If everyone would just accept this kind of behavior they will keep doing it (going mid as last pick when a support is needed).

My question is this. Was I so wrong in going afk? Who is the worse person?