I would worry less about the name, and more about using Blizzard's assets ... The player's avatars and the units/races/leagues icons are ripped straight from them.
More yikes. This goes to my main concern that Blizzard might take issue with it, because people could confuse it for an official app.
At least it's free. :)
Yeah there might be some issues with it if it became very popular. However there are already so many StarCraft apps in the app store that I thought maybe Blizzard is okay with it.
It's fine (probably). While you can trademark and copyright an abbreviation, my searches turned up no matches. Additionally, there are dozens of other sc2-related apps in the App Store.