There should be a cooldown on ranked after being banned
I ganked him at level 3, then killed him again on his way back to lane, and he sold his items, bought Coin, and intentionally fed three times, before finally going AFK. His match history is full of games like this, and he was likely already banned once because there's a big gap in games played.
This could have been prevented by not allowing him to go directly back into ranked, where LP and MMR are on the line.