It's quite controversial. In some places, very wild places, people who go to make videos and photos of the environment are strictly forbidden to interact with animals at all, in order not to disturb the natural flow. However, this is only one exception. Because mostly people would want to save an animal. They're not doing an awful thing, either. It's not a big difference. On a grander scale we do not interfere, sometimes we do, and this sin't enough to disturb the piece. People would feel very bad if they ignore an opportunity to save a life and also will have to watch an animal get eaten by another animal. It's human nature at work here. We're social, empathetic, it will be very hard and mentally damaging for a human to ignore an animal getting killed by another animal, even if iit is normal and natural. It's just subjective. If it truly hurt the nature's course, we'd be forbidden from doing that entirely already, because controlling this is possible.
Technically, from a vegetarian-esque viewpoint, they did do a righteous deed. If a whale washed up on shore, I'm sure nobody would be thinking "that's a natural occurrence and we shouldn't interfere with nature by helping the whale back into the ocean".
Ah yes the butterfly and the spider paradox. The spider needs the butterfly in order to survive if not it will starve, yet in order for the butterfly to live the spider needs to die. However Im not Knives from the anime Trigun.