When you say "inting while drunk", you mean "intentionally feeding, independent of alcohol, while also drinking alcohol".
This is not the same thing as "drinking alcohol and then playing poorly because of the influence of alcohol".
The first one is still inting, regardless of alcohol consumption. The second one is not reportable. The TOS doesn't say anything about playing under the influence of alcohol and/or drugs. It's perfectly legitimate, and flaming someone for it will get YOU banned for flaming.
I didn't watch Meteos. I don't know if he was doing the first or the second. If he's doing the first, he should suffer a competitive punishment (since he's a pro, fine him/bench him for a couple weeks instead of banning him, that's how Riot punishes pros). If he's doing the second, the only thing he can be punished for is if the Twitch/YTG terms of service tell streamers that they can't be drunk on stream, in which case Twitch/YTG is responsible for punishing him and Riot has nothing to do with it.