When you (and i don't necessarily speak directly to August here. Just some general knowledge I believe we all need in our lives) work in a company, any company, you're supposed to know how, and when to, in layman's term, keep your tongue behind your teeth instead of flapping it around. To go out of one's way to insult people like that is absurdly unprofessional. I won't ask question regarding the status of Riot's Public Relations management because for over a year now it was disappointingly clear how miserable it's state must be. I don't think however that Riot's employees lack the basic understanding of human interaction. For that reason, only remaining option for me and many other is to believe that Riot truly does consider it's community "useless" and that it hates interacting with us. I don't have to say just how badly this makes Riot look. And before you bring up that point, no, it's not just his personal opinion. The moment Riot August decided to write from his employee twitter account is the moment we as the community should assume that whatever he says is confirmed and approved by Riot as a whole. If he was writing this from his personal account it wouldn't be that much of an issue. It would still be unprofessional and boorish as all hell though.
Here are screenshots (on different servers for the sake of it not disappearing too quickly. I also recommend you downloading them for the sake of preserving the truth) of the tweet he made. He deleted it some time ago but personally i find it pointless. Internet doesn't forget after all.