Non-Story, although it is funny.
1) From what I've seen of Romo on TV and golf, etc.. I doubt he talks in slang and uses the terms nigga's. It's a 40 year old white guy who loves golf, etc. Maybe if he were 21 and in college he might speak slang like that.
2) Even if Romo does talk like that and I had no clue, it would have been the slang version (niggaz) and not the real bad one (Ni ggers) . In which case maybe a little insulting to hear a white dude saying it , but no super racist and offensive.