I don't know if they're required to play, but Riot employees who queue up and get matched typically are named Riot${something}. I have heard that users who aren't Riot employees with Riot in their name can have their handle renamed.
It was stated on a recent (3 weeks ago?) Twitch steam that in order to be part of the Q&A-ish testers team, you not only have to play League, but you need to be higher elo - I think it was Diamond+? - just to be hired. I mean, it's kind of cool to have "real players" handling the game, but it is a barrier to entry, and definitely furthers the culture of "must play LoL (and be good at it) in order to work for LoL".