People die in car accidents every day. Does she avoid cars?
People drown every day. Does she avoid pools?
People have heart attacks every day. Does she avoid strenuous activities?
People choke on food every day. Does she not eat?
People slip and fall and die in the bathroom all the time. Does she not bathe?
People die. In almost all of these instances, your statistically more apt to die in any of these ways than at Walt Disney World. As a matter of fact, I believe a healthy adult has a 4 in 1000 chance of dying in any particular day. (any Actuaries on the Dis?)
Mission space spins you around. And not even THAT fast or for very long of a time. Most of the issues people have reported on are nausia/dissiness. You are warned MANY, MANY, MANY times that if you have a pre-existing condition, not to ride. I would bet that the miniscule fraction of a percent of people who were hospitalized or died while on this ride had a pre-existing condition.
I count myself as one of the tens of millions of people who safely enjoyed the ride. Even if 100 people died on this ride in the 3 or so years it's been open (which it's probably only 2 or 3 - 0.0000003%), it's still MUCH, MUCH, MUCH safer than riding in a car.