While I totally agree that as a pet, the cat should be welcome indoors, I can understand (up to a point) how the husband might feel if he only ever knew cats only slept in the barn (and only got drinks of milk from the 'owners').
I remember seeing cats with 6 claws on a farm when I was about 10, down in Somerset. Those cats were given hardly any food as their job was to catch any vermin (hence the extra claw, seem to have developed to cope with a hard 'catch your food' lifestyle).
It's not 'solidarity' with the husband, as I expect many women brought up on a farm would have a similar ('harsh') attitude, but this isn't the 50s, post-war, and if you want this kitten (all the more reason to treat with more charity) to be a family pet and let's face it, bought for your daughter, then you need to review this harsh way, and treat this kitten as a member of the family, not a cat which is going to be left to 'fend for herself' (as that's the rather rubbishy way it sounds).
I don't think your husband deserves some of the abuse, but clearly his attitude is out of line with having a 'family pet' and while giving this kitten a home might have been a charitable act, the 'home environment' your husband insists on is contrary to how nearly EVERYONE ELSE in our society considers the keeping of a PET.
Clearly you feel different, but HE needs to see that for such a young cat, with no parents or siblings to have as company, plus foxes (!) around, he's being a shocking example to your daughter, in an animal-loving nation.
FWIW just to give some balance, my (12-ish year old) female tabby has been 'living outside' since mid April, and barely comes in unless there's a downpour. She doesn't like the bullocks (which look in over the back wall) but with the hours I keep (working from home and often up all night) she has every opportunity to come in. She is welcome to come in (and now and again does sleep on top of my duvet) but she will probably spend the next couple of months outside.
No, I'm not entirely happy about it, because of the mixed weather we have had over recent months, but (a) she can take care of herself (5 other cats nearby, she's eldest and trespasses on the 3 tom cats gardens a lot, apparently treating those gardens as her territory too!) and (b) she has plenty of locations (eg garage roof) where she could go to evade a dog (but one of her sleeping places is in below a thick hedge where a dog could not reach her anyway).