Mid lane inted sylas and trolled

Just had a game where the sona mid lane gave away first blood and then disconnected after saying "ok i go troll" in champ select when master yi got banned. Yeah you heard that right he was going to play master yi in mid lane which is bad enough before deciding to troll and go sona mid lane instead. It should be even more severe punishment when only he and 1 other player were not in their promo series so 3 out of the 4 players were basically unable to dodge. He thought he would ruin everyone elses placements after finishing his own and stated how he didn't care when I said in the pregame chat that I will be sending screenshots of him saying he will troll to the boards so he will get banned. There is no way you can allow him to go on scot free after this and i have reported after the game however I understand that with all the false reports you have it's hard to determine what is really an issue and what is a rage at a player who didn't play well or troll reports. Well I'm coming out in the open about this to show everyone that this is no false report and is a serious problem in low elo EUW (yes i'm bad but I try and haven't been playing long) that many players have problems with. Sorry for the long post but I personally feel it is an important issue.