CC,
I think you will find the Geneva Convention ( not that they are signed up to it though ) states one should not fire upon those abandoning an aircraft...... paras are fair game, but crews are not. You are not protecting anyone shooting at what is in effect an unarmed man, true he may have a side arm, but would probably not be in a position to use it..
see
https://www.icrc.org/customary-ihl/e.../v2_rul_rule48