I am not above eating in a grocery store, though I would probably suggest you choose to do it in a grocery store that actually has a dining area - simply picking up a can and eating while walking down the aisle of your local Harris Teeter may not be the best idea.
In the case of Bread and Kabob, they are actually set up more as a restaurant (of sorts) than a grocery, with tables and everything. In actuality, it's a little odd. As you walk in, there is a center cash register area, which may be occupied by someone - if not they will likely be along soon - and this person either seats you, takes your to go order, answers the phone or rings up your grocery order. Put another way, they could quite possibly be rather busy if it's just a single person.
As luck would have it, Bread and Kabob isn't typically all that busy, so neither are they, so instead they walk around, play on their phone and that sort of thing. But they are nice, which helps.
If you are eating in (rather than taking your food to go), you will wait a while as the food is prepared. Nothing wrong with this, as fresh food can take a little while. When delivered, it's rather underwhelming. The rice is fragrant, but doesn't actually have much flavor. The beef kabob is plain. The shawarma is okay, but not great. All in all, I would be more likely to go for groceries than a meal.