The Support's primary goal is to help the team as a whole. The Support's secondary goal is to help give their Bottom laner the momentum needed to make an impact on the game. By and large, that secondary goal takes up pretty much the majority of the early game and some of the mid-game.
Getting pissy right back at a flaming bottom laner and leaving them to die isn't going to help your bottom laner - and it sure as fuck isn't going to help your team. So, if you're doing that...We can't really call you a Support anymore, now can we?
If someone's flaming you, you mute them and report them post-game, not throw an even bigger tantrum and start trolling. Nobody likes toxic players, but at the end of the day, we still do have to play the game with them.
There should be a special report option for support abuse, because it is getting fucking ridiculous.
Just use the "Harassment/Verbal Abuse" report option. There doesn't need to be some special report option for this case, especially when such an extraneous option would do literally the exact same thing as the report option we already have.