You know what I think? There is ONE solution to pass this problem: Integrate such things into the API so EVERY client has to show the Dickbar. This sounds like the logical next level.
As bad as it sounds I think they have some good points about that cause, you know, they want to make some money and integrate some annoying stuff to the official apps. 3rd party apps don't have these kind of annoying things and that means they don't earn a PENNY from those "assholes" BUT they are earning money from their apps which uses the Twitter API.
I know this sounds crazy but I think that's exactly what Twitter is thinking about. They want people to use their official Apps BUT if they use other Apps these MUST HAVE the Dickbar (or whatever) too so Twitter earns money.
Lets see in which direction this will go BUT I have to admit that this "letter" to developers is fucking sharp.