On reflection, I do wonder if the reaction by the person in question wasn't part of that "Not invented here, Do Not Want" thing I've seen before from Americans responding to aspects of culture which are both unashamedly British and can't be parcelled up into the neat, chocolate box, "exportable nostalgia" sector where something like Downton Abbey resides. It's as if the US viewers of these products feel alienated because it's not aimed at them - in fact, it's irrelevant to their interests - and so they throw a strop about being left out and the 'racism' accusation is just a way of legitimating the strop.