I'd like an option to pre-emptively mute post game lobby chat

Riot should add in functionality that mutes someone in the post game lobby if you mute them in game.

Their behavior no longer affects your match, is it really that important?

I see absolutely no reason this cannot be implemented - if Riot is willing to permit muting one/all player(s) in game, they shouldn't have a problem extending that ability to the end game screen. It'd be even better if it would be coded so as anyone you muted in game would stay muted in the post game screen.

However, my personal opinion is that there's some more important things to work on - like the fact the system glitched today and thousands of people had ghost games, and other client bugs/etc. before they add in new features. I know it's annoying (and I'd fully support this idea), so hopefully they'll get to it Soon(TM).

I agree. If I mute someone in game, it should carry to post game.