There's a lot of information about this topic being thrown around, and none of it coherently. There's arguments to be displayed about both sides, so I will try my best to organize them here.
* He was actively toxic on stream, throwing out insults at the player
* He was actively toxic in the in game chat using threats to get his account banned
* Nightblue afk'd and refused to play the game
* He abused the power given to him as a celebrity streamer by contacting a Rioter and using his influence to get a player banned
* According to Riot, you must ask your team for permission to try an off-meta strategy
* His winrate in 411 games (48%) is subpar [source](https://na.op.gg/summoner/userName=Nubrac)
* His strategy actively hindered his mid laner by leeching xp and many are forced to play this strategy against their will
* He was bound to be punished regardless due to a large amount of reports hypothetically already submitted against him
#Finally, Riot Games
* Riot has solicited this behavior for a long time now, as this behavior is not unusual for Nightblue,
* Although, the ban is unusual
* There is an employee at Riot Games who thought this was okay
* Fiascoes like this in the past have always resulted in an unbanning, so why was this person still banned?
* "like this" referring to off-meta picks and strategies
* I do not believe that this Teemo deserves to be banned. He was not actively trying to lose, nor was he trying to troll a specific player.
* I believe that Nightblue needs to be punished in some way for this behavior. His toxicity has been going on for quite some time and is against the rules.
* I also believe that there needs to be a change in policy at Riot Games. I do not believe that someone has to ask before playing a strategy that they are comfortable with, especially when the meta is as toxic and stagnant as it is now. A change in the meta is due, and anyone searching for new ones is welcome in my book.
* Next, there needs to be a change in player mindset. People are against this strategy only seeing it at face value. They are unwilling to adapt and can't accept something they don't even try to understand, and are afraid of being thrown out of their comfort zones. All I've ever been told is that I need to do things outside of my comfort zone to grow, so why doesn't anyone actually try to grow? If this kind of thing will hopefully spice up the game, then I believe that it is a great thing to do.
* As a final side note, I think some of the games that contribute to the subpar performance of his strategy are games like this one where his team just gave up as soon as they saw what was happening. I think if we saw more people adapt to the strategy and play around with it then we would see a higher winrate.