The choice of allocating the 2F or 2E to Etihad is a choice made by Air France only, who is responsible for check in counters on this side of CDG, as they are the subcontractor of ADP for managing the common hub baggage handling system.
In terms of operations, choosing to check-in Etihad bags at 2F can be a smart choice as you have lots of "make-up piers" under the terminal to load baggage in containers. It also brings more clarity in the way operations are ran, by avoiding a cross flow with Air France & Delta bags in 2E.
Finally, many long haul airlines have had check-in counters in 2F in the past years with flights departing from gates L or M (Thai or Westjet for example), ; and passengers were happy with the fast security of 2F and the border check on the bridge to 2E-L.