Your rationale and argument requires providing an excuse for someone's toxic behavior. Specifically, it implies it is more okay to be toxic in response to provocation than for other reasons. It implies this because it would require less strict punishment for retaliatory toxicity (or more strict punishment for provoking toxicity, it's is the same however you describe it).
Riot has stated numerous times there is no excuse for toxicity so this wouldn't work.
Further, a major crux of your argument is that some people are more predisposed to being toxic than others. More so, that special treatment should be given to these people. This is irrelevant because if its true then it doesn't matter how hard the other person is punished - you will still be responding with toxicity.
Punishing one class of players more doesn't "protect" a another class of players.
I get that you struggle with toxicity but I think you'd be best served understanding that you need to focus on your actions and why you seem to be getting so upset. I have a very short temper myself in League yet I manage to be quiet during most games. It's not easy and, in fact, it's very hard. But it is doable.
And you're write, you shouldn't have to edit your own files to remove chat in order to not be provoked. But the answer to that isn't with what you're suggesting. The answer is in understanding yourself.