Does Riot keep a list of what champs are "meta"? We need one, because I don't want to get banned!

I like to play Support Janna with Exhaust and Windspeaker's Blessing.

In a recent game, I had an ADC Vayne who got angry with me in the chat lobby for picking Janna because "janna not meta". They proceeded to be angry with me the entire game, and they went 0/12/0 and we lost, no doubt due to my non-meta support. They told me they would be reporting me for choosing Janna.

At one point they were spamming "kys" in the chatroom, and I muted them so I could focus on the game. But this was probably not a good idea, as I was unable to communicate with the Vayne adequately, and I failed to adapt myself to their win-condition of securing blue buff and running into enemy fountain while the enemy team attacked our inhibitor.

As Riot has recently stated, certain offenses are bannable:

1. Creating a frustrating gameplay experience for my teammates.

2. Not communicating win conditions effectively with teammates.

3. Not adapting yourself to teammates' strategies.

4. Choosing champions that create an atmosphere of disharmony to teammates.

5. Playing non-meta support champions, even if those champions are classified as "supports".

I have clearly done all of these by choosing to play Support Janna. I enjoy this game, and I don't want to be banned for making the game frustrating to all the Vayne players out there.

I had always thought the report system was to remove players who insult and harass their teammates, but I now realize the report system is there to make sure people only play meta approved champions. I didn't know you could be banned for choosing the wrong champions!

Is there some list Riot keeps of Riot-approved Champion choices? I don't want to be banned for making my teammates angry! Please help. I don't want to lose my account for choosing the wrong champions to play.