Holding a game/team hostage reportable or?..

So, I just got out of a game with a guy who was possibly the most toxic individual I've ever played with in a game. Let me give you the rundown here.

In champ select, I get autofilled to top, my least played role. I tell the team I don't play top well and ask to switch, but it falls through. I hover over yasuo as my top lane pick and this guy who was the last ban, outright bans yasuo after seeing and contributing to the chat. The enemy team picks a garen so I decide to go vayne top, mostly because I'm very comfortable on vayne and like playing her into tanks that are melee range. This SAME GUY gets mad because he wanted to play vayne when I picked it and decides to troll from there. He picks sion and we all thought he'd go bot. Now, not only did he pick a troll champ, but he then goes and insults us, calling me and the team autistic. That's not the part that bugged us. If he went bot, we'd be okay-ish. Instead, I go to top lane and he just follows me. For literally 25 minutes, all he did was follow me and just wait until I went to cs and then steal it. My team recommends I go bot, so I base and head bot. Sion follows me to base and then walks bot, blocking me from doing anything. All he would do was stand near me and spam his laugh or something. Our khazix gets a little fed up and says something to the effect of, "come on sion just play right", so what does the sion do? He goes and follows the kha around the jungle and seals his creeps from him. Eventually, he would just go to base, ult out and stop really quick and walk back to base without doing anything. We lost the game because he would follow me around and always leave a lane or a teammate at a disadvantage.

This kind of behavior needs to be controlled in some fashion, and with the implementation of the replay system, it needs to be stamped out. Honestly, this behavior is the most toxic. If someone is insulting you, you can mute them. If someone is int feeding, it's pretty easy to see. This type of behavior was hard to see until now, and replays should be included now when considering something like this. This is the kind of behavior we can't control in game. If he makes the decision to go around and disrupt our team, we can't change that. He will ruin the game for everyone, and he clearly has a habit of it, considering his whopping 32% overall win rate. He doesn't feed and it's not obvious by looking at game stats, but I've literally never had a worse experience playing league of legends, and that is the exact thing riot doesn't want in their game.