Based on the responses here I suspect that the main issue here (putting aside the argument of what the rules are) is the severe lack of common courtesy. I have a very strong feeling that this was the main issue in the Singed case too.

If I suddenly lock in a champion and don't discuss anything with my team mates and i'm passively hostile towards them, they are going to have a much more negative impression towards me than if I had simply been friendly and said to my team "Hey team, i'm going to play something very different than what you're used to, can you be on board even though i'm going to play a very unusual style?"

That's called common courtesy and it goes above black and white "rules" which can be argued for on days.

I have a saying which says "Just because it's not against the rules, it doesn't mean it's ok to be an asshole"

I suspect that this is what happened in this case. It is NOT ok to be an asshole towards others and I believe this is ultimately why this case was brought to light.