It's sort of an odd thing with those merchants. They are at the store 24 hours a day, whenever you need them. But if you put your tent right there and sleep for 8 hours, they get extreme in their sleepiness and hunger. It's like if you're right there watching, they won't eat or sleep. But if you don't stay there any longer than the time it takes to buy stuff and have some conversations, it's fine. Also, I've seen merchants getting food from the food merchant, so they really don't have to starve. I still pitch my tent in the market because I'm never there longer than the 8 hours of sleeping and that's not long enough for anyone to actually starve.