The reason you're being downvoted is because "Why are you living there?" can sound suspiciously like "You shouldn't be living there." It's also a leap to assume the black people living there are going to suspicious of him. You'd be horrified if a group of white people were "suspicious" of a black man living in their neighborhood and this should be no different.
Another question is what will his answer do? How will your opinion of him change or be influence by his answer? Maybe he was born there. Maybe that's all he can afford. Maybe he found an apartment with a particular architectural style unique to that area he wants to live in. Maybe it's close to his friends, or close to his girlfriend, or not too close to his girlfriend, or close to his parents, or easy to get to work, or he often goes into central/southern IL or over to Indiana and doesn't want to drive through the city every time.
There are literally hundreds of possible reasons.