Thank you for the honest explanation... I can see why you are annoyed with this man and his shop.
I would ask you to consider whether one guy you met, who didn't treat you well, is reason to band middle-eastern/immigrant people together. To be honest in return with you, I have met a Swede I didn't like, while on holiday. I do however recognise they are all individuals. I don't imagine they are all the same. My experience was not significant enough to make me want to boycott their products and people entirely.
Maybe he took offense at you asking him to switch to Swedish foods, since you are both currently in Sweden, and I would imagine Swedish groceries are not so scarce that you need to wander into immigrant owned shops and ask them to switch. Perhaps he read your request as a hostile - your goods are not welcome here type of thing, rather than a polite genuine inquiry because you don't want to travel too far.
It's sensitive ground... if your country had been invaded, some of your family killed as collateral damage, and you had to travel thousands of miles, and beg for asylum from here and there, tail between your legs and hat in hand... then you work hard trying organise yourself to get things you find comforting and familiar - you yourself may feel sort of scarce, fragile, a need to fight your corner. Perhaps even traumatised and disturbed from atrocities witnessed and hardships faced.
I am not surprised he is not too concerned about your difficulties acquiring Swedish milk in Sweden... he could have handled it way smoother, and he just made himself an enemy in his own community unnecessarily. So yeah, not a shining example. There is a mis-communication perhaps, you are thinking about convenience, he is thinking about how he will survive in your country. You have different priorities. It always takes time for new communities to fully integrate, and the initial stages are not always pretty. Maybe your family had a similar experience during their early days? Where are they from? I wonder if they had the added trouble of difference in colour and religion?
I do think however you might have benefited from hearing the man's experiences. If he got himself all the way to Sweden, set up a business, and is self-sufficient... he is a survivor, and worthy of respect. He is adding to your economy during tough times, rather than sitting on his ass claiming benefits like he no doubt could. God knows if any of us would have what it takes.
Buy the man's goods, or leave him in peace, I am sure he has suffered enough without your help. And who knows, you might like middle-eastern milk, and increase the variety of your groceries, which is no bad thing, some might even see that as a sign of civilization.
We had a local Indian corner store close some years ago, and it was bought up by Iraqi brothers, who really jazzed up the place. And yes, everything they sold had middle-eastern labeling, but I developed a taste for their fruit flavoured thick bio yoghurts - I haven't drunk yoghurt that good before or since. I've since moved from the area but sometimes travel there just for the yoghurt. And they had some fab honeys on the cheap, the ones with the honey combs still inside, which are hard to come by and quite expensive usually. They were very honest in their pricing, as Islam encourages reasonable pricing ethics.
Their shop mostly had people from local offices buying their flavoured nuts, little packaged cakes, and exotic drinks, it was doing a better business than the local Sainsbury's at lunchtime. Variety is the spice of life. Perhaps if you were not so unwilling to try their goods, you would be happy they were there, and enjoying some different but tasty food. Life is whichever way you turn it. You can turn good things into bad, and you can also do vice versa. Spite never helped anyone: the term "cut off your nose to spite your face" comes to mind.
We end up buying a lot of our groceries from local Korean (they had the most amazing plum drinks with little plums at the bottom of the bottle, also fruit aloe juices), Chinese (fab and endless variety of noodles and dumplings), Indian (spices, 'nuff said), Thai (some not to be beaten dipping sauces)... I could go on... but I dread to think what my diet would be like if I only ever bought from British food and drink.
I gotta' try this Swedish food of yours, it must be unbeatable!