I can only concur with the sensible comments on here from other experienced horsey folk.
Your point A would be the biggest concern for me. Like another poster above I think he’s either being selfish in his own imaginary bubble, or he’s completely clueless and doesn’t know how much he doesn’t know (and it’ll be the horse that suffers most).
Moving from a livery yard, where you have the support and knowledge of other experienced folk, either other DIY owners or experienced staff, just to your own land with your own horse is a big deal- even when you are fully ‘in the zone’ and know your horse well.
To do it off the back of some riding experience, not even full time ownership, 20 odd years ago is fool hardy in the extreme.
A small example, I rode at a RS from 5-13, then had my own at livery (DIY but it was a mixed yard with staff to offer advice etc if you were stuck). I gave up at 18 and returned to it in my early 20s. Bugger me it was hard! I had lost the strength and balance that was previously natural. I had lost the confidence (or stupidly!) of being a teen. I was far more worried now about falling/the safety of what I was doing now. I shared for a year or two then bought our own at 27.
I knew I didn’t want to share forever- your husband is right. It isn’t the same, both in negative ways (you may not agree with the ways the owner does things/you can’t do what you want) but also there is a massive safety net there- experienced people around you who won’t let you cock up monumentally to the detriment of yourself and the horse.
When I got my own we kept him on DIY livery, and the support not just in knowledge but emotional/confidence/encouragement was priceless. Our boy is retired now and we have discussed moving from the SE to somewhere cheaper in the NW where we could have land and keep him at home (obviously with a companion). I’d still feel a bit nervous moving him to a private home now and not having someone else around to bounce ideas off- just the regular ‘hmmm… does he look off to you?’, ‘the grass is coming through/he’s getting fatter… I’m thinking it’s time to get the muzzle out, what do you reckon?’. I’ve ridden for the majority of my life and owned for 17 years. I’ve competed in a variety of disciplines, mainly local level, but in one at an affiliated national level. I am a competent rider and have some low level BHS exams (British horse society). I am not some numpty, I just know there is a lot I still don’t know!
Keeping them at home, managing all the land and decisions that go with it is a completely different ball game… and that’s before you even think about the other issues you mention regarding moving/expecting help etc.