The Americans are sh!t-scared of their own shadows. Anyone of a dusky appearance doing something out of the ordinary is likely to get a very scared police officer screaming at him and waving a gun in his face.
This guy was lucky not to get his brains blown out 'as a precautionary measure'. Americans only recognise the significance of diplomatic immunity when it suits them....Rather like their own stance on war-crimes. In 2002 George W.Bush formally suspended the USA's signature to the Rome Treaty of the International Criminal Court to ensure that no US citizen could ever be tried for war-crimes in The Hague. Hence the USA is accountable to nobody but themselves for their activities outside their borders..... Hardly the viewpoint of a mature developed nation! A cynic might say that a scared population are much more malleable to the wishes of their government... who knows.
Perhaps in 2002 GWB had some overseas adventure in mind ?