True, but with an appeal by Google pending the EU stopped this nonsense a while ago, so right now it could be dealt with differently.
Do Fairphone install the OS themselves, or does their phone assembly partner install it?
If the latter is the case, then Fairphone would have to take an educated guess how many units to order with each OS from the factory … and they would have some re-fitting work to do in case they guessed wrong. Could be costly.