While the video is six years old, this YouTube video from JAM showing The Making of WABC #121 (top of hour jingle)
shows what I assume is/was the master control room and, yes, there is a microphone at the board operator's position (3 mins, 30 secs in on the video).
It would only make sense to have a mic in the control room for emergencies, etc.
Did it occur to anyone that this "work of art" jingle would ultimately be heard by listeners over AM RADIO where all the nuance would be lost? It's like buying a Maserati to drive solely on the LIE. More focus on the talk shows and less on the music would be helpful when programming a talk station.
Despite the number of French horns, WABC's ratings have declined since this gem was produced.