Wirbelsturm
Exactly how would that work?
The FPP guys will only fly with captains.
New DEPs will also only fly with captains
Thus the influx of DEPs will have no effect on the experience level of the cockpit of a FPPs aircraft.
It takes a long time to be a BA captain, so by the time the FPP becomes a captain, experience is most definitely not a problem.
I think it is more likely that BA is just going to be short of guys early next year on the Airbus so needed some more guys online ASAP.