I'm supportive of any efforts @husbandfoodproblems can make to secure a safe return to the UK. Meanwhile, I do want to answer this:
"telling the Op that she needs to let her DH eat in huge amounts unremarked is not helpful"
The man's clearly dealing with an intense, overwhelming addiction. "Remarking" on it will achieve nothing except to make him feel attacked and (subconsciously) afraid. Every addict's response to uncomfortable feelings is to engage in their behaviour - in this case, eating even more.
The only thing any of us can do to help an addict is to listen, without judgement, if they ever want to talk about their problem. OP's husband can hardly be unaware that his food obsession is abnormal! Telling him so won't put any more food in the cupboards. Worse, it will likely push him to step up the secret eating.
So, yes, I do think it's wise to "let him" eat huge amounts. That's what acceptance looks like. You can't stop him overeating anyway, so the strategy I've tried to suggest is one of plenty - with an easy supply of carbs, proteins, fats & flavours to hand, he's less likely to sneak off on his own for takeaways & Wotsits, and more likely to have the emotional space to leave the family food for family meals.
It will require a different approach to shopping, and DH might have to be brought on board so his "personal" eating spends go towards the budget chickens, etc, to keep him satisfied. That's up to OP.
I had an eating disorder - other end, I was anorexic but, like most anorexics, I would binge occasionally. I remember the feeling: a kind of desperate fear of scarcity, and angry rebellion at the thought I wasn't "allowed" to eat 50 packets of crisps or whatever. I still get it sometimes; now I understand what's going on, and just let myself have the cakes/crisps/chocolate. I know my body will self-correct my calorie intake because my appetite is now well-adjusted.
A big part of the cure entailed stuffing my kitchen with more of my binge foods than I could possibly manage in the most extreme blowout. Now I'm not saying this is a cure in itself, far from it! But the sense of security I gained from knowing the foods were all available, in huge quantities, whenever I wanted some was essential to the rest of the work.
We can't make Mr @husbandfoodproblems want to move past his disorder and his passion. But we can help him to feel less guilt, shame and fear of it. That may well improve the atmosphere at home.
As to what DS makes of it - it doesn't sound as though he's heading that way himself, and OP is capable of explaining Dad's abnormal behaviour as a maladaptive coping mechanism, in child-friendly terms.