I know this is likely a rhetorical question, but the fact that we are all using Bitcoin suggests we already have trust issues, whether that's the government or third parties such as the banks. Obviously, you have the speculative investors too looking to make a quick buck, but the majority of long term users here are here for a reason.
Has it even happened, or does it seem probable to you, for some agency to request any kind of take down due to the advertisement of a service that might be one of the top targets of the authorities
As for this question; I imagine certain parties have tried this on. Probably not government level agencies, as I said I think they'd need to have grounds to request that information, and would likely need to be investigating a user for that information to be requested. However, I imagine lower level people or companies have requesting this information of theymos. I mean, he's probably got all kinds of requests from the professional to the damn right absurd.