OK.
My understanding is as follows:
An arahant is in the same position as a puthujjana in the sense that they are exposed to arammana due to their past kamma.
However, since arahant has removed all samyojana, arahant will not generate kamma vinnana regardless of any arammana.
I think in the sentence “But that specific arammana (to kill anyone and add another finger to his collection) would not arise in him ever again,” it should be kamma vinnana instead of arammana. Thank you.