I think there are two separate issues here: What constitutes life and what constitutes personhood.
I'll have to think more about the "life" part, but I don't see how humans can have the capacity to create "persons" from raw materials outside of themselves. (In other words, "machine life", like Data and the Cylons.) The reason is that a key, unique component to persons is free will. Choice. But we don't even understand, ultimately, where our own choices come from, and so at best could only program a simulation of choice into machines, not choices as they truly manifest from within us.
(In the new BSG they work around this idea by suggesting that God gave the Cylons true personhood, even though it was humans who first constructed their physical forms.)
Because we don't truly understand the nature of choice, at best machine life could only be like animals. So we are at least justified in that sense to treat machines no better than animals.
But the further difference would be that we didn't make animals. Animals were made by the same God that made us, putting us somewhat on the same ground they are on in terms of the "pecking order" on planet earth and who is justified in doing what. But we make machines. They wouldn't be here if we didn't. So we're justified in treating them however we want... until God decides to implant them with personhood. ;-)
That would be my take on it.