Not true. I have darker skin than Obama and I put on sunscreen and a hat when I'm in the sun for any period of time. My father has had basal cell carcinoma removed from his ears and cheek. Obviously, it is much less likely to happen than those with whiter skin...but it does happen.
If you can get sunburnt, you can get skin cancer, I guess.
But a dark skinned person’s gotta be in the sun a hell of a long time to get any burn to speak of. I’m one of those unlucky ones that burns bad. I can feel hot stinging/tingling deep in my skin within seconds of direct sunlight touching my skin.