The photo is referenced and dated at the bottom. It's an odd choice but if they other tables are covered in the same way with historical photos it's not something to get worked up over, as it was a part of American history (again I don't think the photo was a race related hate crime from the era, although it could be). But it would be no different than having the photo be of an indian reservation.
I wonder how long that table has been in the restaurant, I'd also imagine it's not a custom piece that it's likely produced in bulk.