In reply to:
I agree. With a prussik, adjusting the connection point would be smooth. On the other hand, literature generally indicates to always back up a prussik. Given the exercise, I think we should view this connection as a primary.
One could use two prussiks at that point. Still, various literature about the prussiking-up-a-rope exercise indicates to periodically back up them up (e.g., figure 8's on bytes clipped to harness).
Given this, I've come to view an unattended/unweighted prussik with suspicion.