Tricky topic to take on here. The test you propose is interesting. I didn't get a "no" in my heart when I initially read your question.

I felt more like, "I know if I were enslaved, I'd be doing all I could to get out. So would (and should) any enslaved person, if they're able. Skin color is irrelevant."

Morality = principles concerning the distinction between right and wrong or good and bad behavior.

The thought experiment is understandable. The killing response is clearly justified in terms of reciprocal behavior. But I don't know if eye-for-an-eye thinking is moral.

Maybe we shouldn't have had slaves in the first place - and THAT would be moral. If only.