Why? If the stream is not HDCP (which currently it cannot be by law), then why does Aereo have a special obligation to treat the content as protected? Congress

Why? If the stream is not HDCP (which currently it cannot be by law), then why does Aereo have a special obligation to treat the content as protected? Congress could end this whole debate by allowing broadcast DTV to require HDCP, which they have so far explicitly denied. [ https://en.wikipedia.org/wiki/Broadcast_flag https://en.wikipedia.org/wiki/Broadcast_flag ]