Did you explain it the way you did here to the neighbor? He may think you are anti gun and doesn't want anything to do with you. If you did explain I would think kindness would be to invite the hubby over to shoot with him.
My oldest son who served 8 years as a 19 Delta "Cavalry Scout" still hits the ground if the sound is loud enough and unexpected. He enjoys shooting and it helps relax him because it takes his mind off all his troubles and he just concentrates on his shooting.
Thank your son for his service for us here in the Forum sir.