I know there are some people in the DMV who didn't follow the Orioles but for the most part that's who baseball fans here followed. Some are in denial over this but there is a whole generation of Os fans in there 30s and 40s who will probably always be Os fans to some degree. It's still irritating to hear the local radio and TV give their scores as if they are the home team.
I get it. When I lived there there were no Nationals - but local radio, tv and newswriters have to cater to their audience and the audience has a contingent of Orioles fans who, if ignored, would cease listening, watching and reading. Then those talkers, broadcasters and writers lose their job - all because some butthurt baseball "fans" don't like the Orioles.
DC residents rooting for a club that is actively seeking the liquidation of the Nationals is treason, pure and simple. Yet sadly these do still exist - Boswell, George Will et al.
Call the Wahmbulance; or better yet, BiL's Fan Police Brigade. People can root for whatever freaking team they want.