Would the old man be the hero without the woman in the basement?
If he didn't have the woman trapped in the basement, would the old man be the protagonist in this movie?
Whenever I see anyone posit that the old man is the hero, I then see others rebut by noting the way he kidnapped and forcefully impregnated the woman in the basement. Does she serve as his only claim to villainy?
Without this detail, the old man is simply defending himself from people who broke into his home, stole his money, drugged his dog, and attempted to gas him while he laid in bed at 2:00 AM. They provoked him, in other words.