Actually he was pretty stupid doing what he did.
I could not possibly disagree more. Muldoon not only knew he was likely sacrificing himself to save Ellie, but resigned himself to either the most lucky break in his life or the most gruesome fate imaginable.
If you think his actions foolish, read up on man-eating leopards, in particular
The Man-Eating Leopard of Rudraprayag by Jim Corbett. The reason I bring this particular case up is because leopards are known for their ability to sneak within literally less than a foot of their victims before dealing the killing blow. In the tale mentioned above, Corbett (The author of
The Man-Eaters of Kumaon regarding man-eating tigers in India) recounts his several-year-long quest to dispatch the leopard. During its reign of terror, the leopard killed and ate in excess of 125 people, many of whom were seasoned hunters, not just of big cats, but of leopards and even Indian man-eaters. Despite their talents, they were dispatched in the end and proved little more than hearty meals for the skilled hunter.
That's an instance when a man-eating predator is capable of getting within close proximity of its victims, many of whom are trying to hunt it.
Most people are familiar with
The Man-Eaters of Tsavo by Lt. Col. John Henry Patterson, the pair of male lions who harried the builders of the British railway and bridge over the River Tsavo in Africa. The lions had a combined total of kills close to that of the Rudraprayag leopard who still holds the high total for human kills by a solitary man-eater. These lions not only killed a great number of skilled hunters from numerous continents, but outwitted and cowed a tribe of Masai warriors, the Masai boys who had a traditional right of passage of killing a lion with only a spear, brought in to help hunt the man-eaters (they deemed the creatures to be demons incapable of dying by human hands and abandoned the hunt). The terrain of Tsavo is unforgiving and maligned for its hardship. Its thick bushes composed of thorns in excess of an inch and often used to make boma, are believed to be a contributory factor for the male lions in Tsavo to have evolved manelessness. Point being here that a number of skilled hunters, extremely talented killers, entered thick brush with a pair of cooperating man-eaters and were slain. Patterson hunted and successfully killed one of the man-eaters in thick brush (subsequently killing the other in a rather open area surrounding the main railway work station). Corbett hunted the leopard nightly in the very trees that the leopard excelled in hunting from and in the thickest parts of the Indian jungle, eventually firing the killing shot from one such tree.
In order to hunt a predator which predates upon man, it's often necessary to delve into situations where one would not necessarily like to find oneself; but that is the price of successfully dispatching a skillful man-eater. Man-eaters are a hobby, and if I had my way I would probably be studying them for a living but to my great regret my loved ones wouldn't have allowed it.