Like Matt is saying, I have swam with atlantic blacktips in the wild, without incident, even been spearfishing around them without incident.
However, startling a large fish is not a good idea. I might start wearing a mask when I fed, and extending myself out further, and further into the tank as I fed.
Sooner or later he would be used to seeing your whole entire body, but he would also associate that with food. At that point you have to start asking yourself what kind of risks you like taking.
My shark has only almost bitten me once, and she is pretty good about knowing the difference between food, and fingers.