Yes that's true but females of almost any species will protect their young to the best of their ability, often quite aggressively. As for being in "musth", that's true too, but that's an exception to their normal behavior. I was in Kruger National Park(SA) in November, not far from Hwange actually, and saw these elephants from up close. There was an elephant crossing the road which clearly seemed to be not in its normal state of mind, though not being aggressive. The driver parked at a safe distance and explained what Musth is. It's basically when young male elephants are 'horny' with high levels of testosterone in their blood. After the elephant crossed and safely retreated into the jungle we continued on.