I wonder if your DH is managing his stress by buying food? He might not even be aware of why he is doing it, just that having those extra things stashed away is comforting. Which would explain why he responds by getting defensive when challenged, if he doesn't know why he is doing it, just that it's an strong urge, and threatening to curb it makes him uncomfortable and anxious.
Just asking because the combination of not being able to pop to the shops (shielding), sudden difficulties booking my usual delivery slots, and then the deprivation of having a long awaited delivery turn up with half the much needed items missing has certainly triggered all my hamstering instincts.
Normally I'd order a grocery delivery with all my favourite vegetarian foods from one of the major supermarkets once a fortnight, topping up on fresh milk, fruit and vegetables from the corner shop between deliveries.
I have struggled with eating disorders since childhood, with the help of therapy I developed strategies that have allowed me to live for the last 3 decades without constantly obsessing about food. But when my first delivery arrived without eggs, baked beans, rice, pasta or bread, and with half of the fruit and vegetables also missing all my food demons escaped and got stuck into taunting me again.
It didn't help that it took so long before the letter arrived confirming my vulnerability under the covid rules. The fact that I am disabled, am no longer able to drive, and have been reliant on supermarket deliveries for years didn't seem to be taken into account anywhere. A great deal of my time and energy was spent stalking grocery delivery slots.
Sometimes I couldn't get a slot for several weeks, other times I'd manage to snare two in the same week, from two different supermarkets. In which case I'd greedily book both slots, so that if the first delivery arrived with important items missing I'd have a second chance at getting them from the other supermarket. If the first delivery arrived with all the ordered items then I'd cancel the second delivery, to allow someone else to use it. And anyone who wants to berate me for it had better never have gone to a second shop after the first one they visited lacked some of their own "essential" items.
I also started adding to the second delivery several different sizes or varieties of any of important items that had been missing from the first delivery. Having realised that if they'd run out of 1kg bags they might still have the 500g size left in stock, but wouldn't always provide a substitute, or if they'd run out of large free range eggs they might still have mixed size organic eggs. Which sometimes resulted in the second delivery arriving with both a 1kg bag and a 500g bag, and 12 large and 12 mixed sized eggs, so I'd end up baking and making a big crustless quiche as well as eating breakfast eggs. I also took to adding a couple of boxes of tofu with each delivery, so that I'd have a stash in the cupboard and could still make breakfast scrambles if the Great Egg Shortage reoccurred.
Normally I'll have one bottle of hand soap on the go, and one in the cupboard, ordering a replacement when the cupboard soap was moved to the sink. Until the time when I tried to order and all the hand soap had sold out. Same thing with bleach and toilet paper. When the reserve was in use and dwindling I'd start to get anxious, and when they came back in stock I'd want to have one in use and TWO in the cupboard.
I've even taken to buying things that I'd never normally buy, like chocolate, sweets, crisps and peanuts. Normally I only buy healthy stuff in the supermarket deliveries, forcing myself to hobble to the local shop for the unhealthy stuff. That might be one of my eating disorder coping strategies, I find it more difficult to run a load of unhealthy stuff past the checkout staff if I'm there in person, rather than an anonymous online shopper. But since I can't go to the local shop I have felt entitled to add crap to my supermarket shop, and the damned supermarkets keep having special offers on all the highly processed, empty calorie foodstuffs that are designed to "keep" for months, so you can rationalise buying a lot more than a single treat, yet the darned things don't keep for months because I always end up scoffing them when I'm hungry but too exhausted to stand up and cook.
I don't drink, but I do use Sherry, Madeira, Port and red and white wine in cooking. So I tend to have an open bottle or two of the fortified wines on the go in the cupboard, and ice cubes of left over red or white wine in the freezer ready for the next risotto or Gigantes plaki. So when delivery slots became rarer than rocking horse shit I started adding an extra bottle to the deliveries. I even invested in a bottle of whisky, since the one I bought in 2008 was almost empty. I only ever drink whisky with hot water, honey and a squeeze of fresh lemon juice if I have a very bad sore throat, having discovered that after 2 or 3 of them my throat stops hurting and I am able to drift off to asleep very easily. Which is a very long winded way of saying that I don't drink alcohol for entertainment purposes (being more into herbal remedies) but I've bought more of it since lockdown than I have in years.
So DH has my sympathies. We are all coping as best we can, in our different more or less useful ways. Playing fridge and freezer tetris is better than having nothing to eat. Or worrying about not having anything to feed your family if conditions deteriorate further.
Perhaps it'll make him feel more comfortable if you do an inventory of food stocks, checking the dates on everything? You could compile a list of menus that you are able to cook with what you've already got, using the things nearing their use by dates first. Then you could make a second list of meals you fancy having where you don't have all the ingredients, writing a shopping list of the missing ingredients for him to take with him on his next big hunter gatherer expedition. That might help him resist the lure of unnecessary impulse purchases.
On behalf of all stressed hamsters who find comfort and security in a well stocked pantry I urge tolerance and understanding. Now I'm going burrow back into my big nest of paper hankies and don't want to be disturbed unless you brought a carrot.