In the situation you describe, as in so many situations, don't think about what you can't do (turn the a/c on the taxiway), but about what you can do! You have an arrival 35 nm away, so we'll call that 7 minutes or so. You have a runway, at which your A320 is now pointing. You have exits from the runway, should 7 minutes be too short a time to backtrack the A320 the entire length of the runway. I'm guessing in that situation, the instructor wanted to see you getting the a/c away as the first dep from the new direction, preferably before the first arrival.
Anyhoo, what you typed here of your report really doesn't seem all that negative to me.