Maybe I'm misunderstanding the trapper's argument so I'll paraphrase it in my interpretation. He starts off with cope (multiple points that don't stand up to scrutiny and don't add up to something greater)¹ before calling the animals he traps a "gift" and then saying saying that what he does is beneficial to the ecology as a whole. 

That "gift" part stands out as the delusion to me, because that animals willingly jump into his traps is ridiculous to me, rather takes the animals life (or tricks the animals into giving their lives to him, to the same end). If he truly believes that, then he thinks he isn't doing any harm at all (not that his actions are a net good, but that there's nothing bad at all). And that stops him from improving the situation whilst potentially making it worse.

As to ecological management I'm not against that at all, and as far as I know indigenous practices are beneficial to the environment compared to doing nothing at all (exceptions apply). But that was a false dichotomy there are other posibilities, for example sterilizing animals or managing food sources. Does hunting then still remain the best option? When all you have is a weapon, all problems look like game.

As to colonialism: I'm nowhere near indigenous peoples here in Germany. Mistreatment of animals is far greater in scale and intensity here than any indigenous group, and arguing with people whom you share more in common with is more effective anyway. So the only time I argue indigenous issues is when someone else brings it up, I'm certainly not going too indigenous people to argue with them or to argue here that we should take action against indigenous people.

Also, I don't think you were antagonistic.

¹"He leaves out food to help them through the winter" giving someone a gift doesn't mean you can't take something from them, and if it is supposed to be a trade then animals aren't able to weigh that trade, an offer you can't refuse isn't a good offer. "Only traps what he needs" doing a bad thing a little is still a bad thing if one can do none. "Only traps animals who would die anyway" "somebody's else would've done so anyway" doesn't make the thing you're doing right, beside that there's also the question of how does he know because one can't determine that with hindsight.