We may not know just what political stance Activision Blizzard has decided to take on the issue of S.134: The Violent Content Research Act of 2013, but we do know the company has hired lobbying firm Akin Gump Strauss Hauer & Feld to lobby the Senate over it. The bill calls for the National Academy of Sciences to study the correlation between children playing violent video games or watching violent video content and violent behavior -- and could be a stepping stone towards more legislation aimed at restricting game sales.
There have already been studies on video games and violent behavior, but the results have been mixed: ask a dozen experts and you'll get a dozen different opinions on how violent content might affect violent behavior. To this end, the bill also calls for study to identify gaps in current research. However, it's questionable whether more research will give us a real answer or just more mixed signals. In the meanwhile, game-makers are definitely edgy about how this could impact their bottom line... which is probably why Activision Blizzard has jumped on the lobbying bandwagon.