Probably don’t want the bases and fly patterns to be determined. From there they can line up the AA. US isn’t the greatest at making their flight patterns unpredictable
They've been flying surveillance drones along the same paths over the Black Sea for more than a year now - they leave their transponders on and you can look up the flight paths online (try FORTE11, for example). The US doesn't care if the Russians know where the drones fly out of.
