If bringing fire to a species lights and warms them, but also gives the means and incentives to some members of this species to burn everything for good, you have every ethical freedom to ponder whether you contribute to this fire or not.
If bringing fire to a species lights and warms them, but also gives the means and incentives to some members of this species to burn everything for good, you have every ethical freedom to ponder whether you contribute to this fire or not.
For your fire example, there's a difference between being Prometheus teaching humans to use fire compared to being a random villager who adds a twig to an existing campfire. I'd say the open source contributions example here is more the latter than the former.
"It barely changes the model" is an engineering claim. It does not imply "therefore it may be taken without consent or compensation" (an ethical claim) nor "there it has no meaningful impact on the contributor or their community" (moral claim).