So is it okay to kill a thousand monkeys for funsies because it is “insignificant in comparison”? No, that would be highly unethical. There is no societal benefit to such a action, so nothing can justify the action. No matter how few animals you killed that is infinitely worse than the meat industry in aggregate.
How about if I kill 1000 monkeys to produce junk science thus slowing the rate of scientific progress? That is even worse since not only is there no societal benefit, there is societal harm. No matter how few animals you killed that is infinitely worse than the meat industry in aggregate.
Well guess what, Neuralink is almost certainly doing junk science as evidenced by their total disregard for basic established scientific protocol. The problem with Neuralink is not that they kill animals. I am okay with killing animals. What I am not okay with is the bad science.
When you are running experiments to validate if your implant is safe, and you use a unapproved adhesive known to be neurotoxic to attach the implant, then the monkey dies to the neurotoxic effects of the adhesive, you did not do any science, you just learned that you should stop ignoring instructions. A child could have taught you that. You are not pushing the boundaries of knowledge through the sacrifice of animals, you are pushing the boundaries of primary school. You do not get to kill animals to learn that.