You don't get a punishment if you don't get reported.
Okay. And?
Thus, if you get reported more often based on the external factors(like your pick) you are more likely to get punished for verbal stuff not crossing thresholds for people who get reported less often for exactly the same behaviour.
......Okay. And?
If a player gets validly reported for toxicity, regardless of whatever their pick is - meta, non-meta, god-tier, Soraka, what have you, they're getting validly reported, and consequently punished fairly.
How is that inequality? Is it just because of some supposed community predisposition towards reporting players for off-meta picks? Despite, at the end of the day, them having committed an offense that made the report against them valid?
At the end of the day, a toxic player getting punished is a toxic player getting punished. Whether or not they played according to the meta doesn't matter.