It is a sad occurrence and, while I didn't advocate his touchy feelly style, he did do a lot to educate people who perhaps wouldn't have watched a 'normal' wildlife TV programme and, as such, he will be sadly missed. My heart goes out to his wife and kids.
I have to confess that, when I heard the news, I immediately assumed he had been manhandling the ray and that is why he got nailed. After all, that is what he does with most of the animal life on his shows. However, after reading and talking to a lot of people closely connected to Steve and the incident, it does appear it was just a case of the ray feeling boxed in by Steve and his cameraman and lashing out. If it had got him anywhere else but the heart, he'd probably still be alive, and by the sounds of it, it was nothing to do with the venom, but the impact of a stilleto-blade-like barb going straight into his heart that killed him. A very unlikely scenario, but these things do happen.
Mark