I believe that no matter how careful and experienced with wild animals you there is inevitably going to be one time that you slip up and get injuried or killed by the wild animal you are handling with so I don't think it's much of a surprise at all that the preacher died from a snake bite.
A snake has venom to protect itself from anything disrupting it's natural activity. They protect themselves from other animals and humans, preacher or non- preacher. A preacher who dies from a snack bite has exaggerated his lucky streak. A preacher has no special powers that can get rid of snake venom.
It's the same thing with the crocodile hunter Steve Irwin when he died. Everyone was sad, because he was such a brilliant conservationist, but there was no surprised. If you spend your life fiddling with deadly snakes, it's only a matter of time until you're bit and possibly killed by one.
No, when you handle a lot of dangerous snakes, there is going to be a time sooner or later that you will get bit. I think that they just need to keep medicine ready so that when they are bit it will not hurt them to the point of dying.
When people like this play with deadly animals and poisonous creatures, you can only expect the unexpected and know that sooner or later something bad is about to happen. This was just an animal being itself, and a preacher or man not putting enough caution in what he was doing.