As I understand it, if autothrust is disengaged the FBW Airbus thrust levers work the "old-fashioned" way
If they do, how many pilots do you think would know where they need to be physically positioned to provide cruise thrust? Since they spend all of their normal operation in a fixed position, I find the aforementioned pretty unlikely.
I know exactly where the thrust levers need to be with the trim between 5 and 6 to provide a safe starting point if things go really really wrong.