Coming twice a week he should be pitching in like a proper family member, tidying his own room, helping to lay the table and/or clearing up at the very least. You’re not running a bloody restaurant. At 15 I’d have been livid if someone tidied my room so I find that very odd.
If DH is so precious about food he can shop and cook. My DSC are much younger and one can be very fussy. DH does all pick ups and drop offs and I make dinner when he’s getting them so we all have more time to sit down together, I make sure meals are something we all like and have only ever had gratitude from him and thank yous from them. I’m happy to cook but they help sort plates, table, candles etc and then everyone helps clear up. They’re only young but they put dirty clothes in the basket and we wash only what’s in there, they put clean stuff away. We both work ft and I'm no one’s skivvy, everyone who lives here (we have DSC every weekend and a night in the week) does their part to keep things ticking over. They’re absolutely not guests, they’re part of the family and the home and that comes with rights and responsibilities. We want them to grow into capable independent people and that comes from learning to clean up after yourself, pitch in, do things which benefit other people, converse politely, be appreciative and make an effort when needed.
Your husband isn’t doing his son any favours by treating his 15 year old like a pampered prince and he’s bang out of order expecting your DD to clean up after him. Stop that crap right away. It’s an awful message for your DD and while his son may be a standard grumpy teen your DH should be thanking for what you do for both of them, and it’s not “helping” it’s being an equal member of the household.
You don’t have to collect him either, if DH wants him to have a lift he can do it himself.
You know this isn’t right OP. You have to model healthy dynamics for your DD even if DH is happy not to for his son. Do you want her expecting to have to run around after a demanding man in her future life? I hope not.
And I’m all for treats and doing lovely things for DC. I put pjs on the heater so they’re warm after bath time, they have favourite foods in, I play endless Lego and we see god awful Disney tripe at the cinema, they’re cherished and loved beyond belief, but they’re not spoiled and they appreciate extra effort and show us the same.