That player played over 3,000 games, that's what 2.9% of his games possibly over years, where the other 97.1% of games he may have been courteous and helpful to his entire team? Chill out and quit raging against the ragers. That means out of 100 games on average he's raged 2-3 times over some reason likely regarding a team being really dumb/trolling them. One week is more than enough time for them to think about how they affect other players and maybe get them to chill out a bit more, much like you need to regarding them.
Out of 100 games how many times do you get guys totally trolling you? Honestly <3% does not deserve some sort of extreme punishment. Next time check their # of games before making a thread like this. Also yes that's their lifetime record that riot quoted which includes all 3,000 or so of their games many of which they were likely provoked in giving the low % of offenses.*
I'd be willing to bet 1,000 IP your record looks worse than theirs in regards to % of games offended (you know, assuming you'd post on your main).
*Disclaimer: Obviously I don't know that that's true in a minority or majority of their cases, only that it's very likely in at least some of them. But you also don't know the details behind those reports. If you use the tribunal you will also notice even guilty players generally have a few false reports amongst the legitimate ones, maybe 25%, I didn't even bother considering that in this post though.