Either way would work I agree, but I think I'd lean slightly towards mapping it.
1.) It does represent an "obstacle" that must be dealt with. Being told your next turn is in 3 miles and then coming upon the roundabout in the dark of night could be surprising, confusing, or even dangerous (if the person is stupid and relying on Waze too much).
2.) The road appears to change names here. The roundabout makes that change more obvious and stops (or slows down) an editor from trying to "fix" things and propagate one name to the other segment to delete the junction representing the current name change.
3.) Someone is going to think there should be a roundabout there. Do you trust the average editor to do it right?
I think it is really #2 that pushes me over the edge here.