Having assigned food

Me and my husband disagree on something. It's not a big deal and it's honestly not my hill to die on. He has food such as eggs, milk, and cheese that is specifically designated for his son and has his son's name on it. My step son is a vegetarian. He stopped eating meat when he was 12 because he likes animals. He's been vegetarian almost 4 years. He will eat animal products such as eggs, milk and cheese but only if they're from a humane company. My husband goes to this specific market when getting him food because the people who own the market also own a farm which both my husband and step son have been to. The animals are taken care of. They aren't pumped with hormones and they're treated humanely. So my husband buys from them. My only issue is he specifically marks my step son's name on it. So if we are out of our milk I have to go to the store to buy some because I can't touch my step son's milk. My husband's reasoning is it is expensive so he doesn't like to go there often and he wants to make sure my step son will eat because there was a period where he was completely vegan and wasn't getting enough to eat. He went back to vegetarian after my husband found this place. My step son has been in the hospital for some nutritional issues and not getting enough to eat. Now they've found a decent compromise and he's healthier. Just has to take a few iron supplements. I sometimes worry this will come off as favoritism to the kids we have together. Like their brother gets his own assigned food that they aren't allowed to touch. Like I said not a hill I'm dying on and not gonna argue over it anymore. Just wondering

Edit: He doesn't get everything there because it's very expensive and we go through a lot. What he gets there may last us a week in this house but would last my step son almost a month depending on what he's eating. It's cheaper for him to get all our stuff from Walmart or other grocery stores since we as a family go through so much

Edit2: We don't actually pay for his iron supplements. The doctor prescribes them and insurance covers them.