In any case, I don't think that Toni was questioning whether Button's Twitter account was legit. I think she meant that someone authorized by Button -- such as a publicist -- might be tweeting on his behalf. Nothing wrong with that. Some public figures enjoy tweeting with their own fingers; others rely on communications professionals like Toni.
Of course it is true that impostors can set up unauthorized Twitter accounts that they claim belong to celebs, but that's another kettle of fish.