[As I recall..., the chief objection to this service plan came from people in upper Manhattan who were upset that their MAIN SERVICE WAS BEING RELABELED "Q"!!!!! They kept citing the Billy Strayhorn song (performed most famously by Duke Ellington), "Take the 'A' Train."]
The Q as weekday-only express was one of two main complaints. The second argument was that a particular line in the song - "You'll get to Harlem in a hurry" - was socially (if not legally) binding on Transit, and constituted an obligation to keep the A as an express service. (Naturlly, they wouldn't have minded a Q express in addition to the A express!)
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[Funny thing is, if NYCT(A) had called the 207th Street-6th Avenue-Brighton service "A" instead of "Q", probably nobody would have said a word and the plan would have gone through unchallenged!]
Actually, the proposal WAS reworded to that effect in response to the Ellington/Strayhorn complaints: the weekday-only Q express became the A, while the full-time A local became the C. Of course, all of that became water under the Manhattan Bridge anyway.