We're basically some of the last megafauna. There's smaller prey that is an easier target for them with less risk to them personally. Predators generally avoid prey that can injure them. It sounds like the Indigenous people already had some experience around these creatures that was shared to the researchers and I am sure the researchers took great pains as to normalise their presence and not make them feel cornered or threatened. This species is about ten times older than us, being hyper aggressive and violent is a really bad trait for survival, generally. "Survival of the fittest" gets really misconstrewed.
