All tasks we ask of our kids should be age appropriate, and considerate of the individual. I would expect a 4 year old to manage what my older boys can do now with some experience.I'm definitely not a hard-core chicken owner, but the thought of having an indoor chicken turns my stomach, to each his/her own. I feel the same way about cats, and those are socially 'acceptable' indoor animals, haha.
Although my 4-year old could have retrieved the birds for me, at 4, I'm not too interested in having her "help" with processing chickens. It was hard enough corralling my adult helper!
My husband is not a wuss, but a total jerkface when it comes to helping me with anything chicken-related. I should serve him tofu while I make myself MY CHICKENS, as he calls them. Well, technically, he calls them YOUR D*** CHICKENS. I have no idea why he's so hostile to them, but whatever. Tofu might set his head on straight.
My DH started to enjoy the chickens when he could throw out oats or corn after a long days work. HE has come to really like the birds; and doesn't mind when one is for dinner. DH helps with coop building and the feeding, too. Sorry your DH is a headache. My DH loves all animals so chickens are not too far a reach for him. Hopefully your DH is still young and trainable, lol.