Unless there is an obscure TERPS Manual exception, the only explanation I can give is that IT'S KDCA AND THE FAA CAN DO WHAT WANTS. The LDA 19 is outside of 30 degrees, as is the ROSSLYN, the course does cross the extended centerline but the ROSSLYN doesn't; the descent gradient is less than 400 ft/nm. They both should be circling only because of the course guidance outside of 30 degrees of runway centerline.
GF