I think the crucial question is does this 'model' have the capacity to develop those things. If it does, that creates a serious problem for continuing research along these lines. If not, then I don't really see them problem - in that case I would compare this to growing and running test on kidney or liver.
"These humans, they might have agency and free will, but they don't have fuqismatk or missildrigg like we do and so it's ethical"
let me help you take your example further:
"These humans, they might have agency and free will, but they don't have fuqismatk and missildrigg, so us gakimiking and monikiking their brain should be ok."
I don't buy this argument, I only feel like I have free will, as a model of my brain would. How could you convince me otherwise?
Under what conditions would you say an entity would (hypothetically) have "free will"?