Earlier quoted context omitted.
Okay, on day 19 three of them are clusters of cells, how about day 280? How about year 5? I think the argument is that a majority of people would find it unethical to continue to develop viable embryos, and even more unethical to conduct research on them were they to mature.
What if we gave a dog a human brain? What if we gave a robot a human consciousness? Just offering some more scenarios that didn't happen.
Even a dog with a dog brain shouldn't be subjected to arbitrary experimentation and pain. If it is sentient, then it should be treated with respect. A robot with consciousness should also be treated with respect, and if it wants love then it deserves love.