Leaving aside the PETA woman (he won't be hanged), the revulsion stems from the fact this despicable act exemplifies the worst of humanity's pathetic, self-gratifying attitude to the natural world. I for one find it troubling for our future as a whole that there are people - wealthy people from powerful societies - who think that this is what other creatures are for.
Remember though that this individual is only a particularly egregious specimen of the sort of attitude that most human animals take toward non-human animals anyway as a matter of course every single day, as things, objects, commodities who either don't possess consciousness, sentience and emotion at all - a few scientists still defend the Cartesian line, though they're a tiny and dwindling band - or if they do, they don't really matter.
This lamentable tooth extractor has the money to have bought himself a luxury trophy hunting holiday in Africa, but in terms of basic mindset I can't see how his attitude is in any way different to somebody who sits down to a meal containing meat, which is another example of an activity which is pointless in being unnecessary (people need to eat; they don't need to eat flesh) but carried out gratuitously, as it were, purely for self-gratification.
So according to shaker all the meat eaters on here are as bad as the dentist.
Shaker always takes it a step to far, IMO.
Most of us are hypocritical enough to waive morality when it comes to killing other animals to eat.
Evolution-wise, of course, we have developed as an omnivorous species, but evolution knows nothing of morals, which are a human invention. If we are going to argue that killing other animals unnecessarily is immoral, then we have to face the fact that eating meat is immoral ... because we can be quite healthy as vegetarians.
However, it's a moral maze, because there is no justification in separating plants from animals in this respect. They are living organisms, and we curtail their lives to eat them.
In short, morality is a mess!
