Just, no.
1. You're speculation is off the walls and just BS
2. Yeah, some of the mice were sac'd for the paper, but they plan on studying this model into adulthood
3. "...it's pretty much illegal to form a sentient being with mixed DNA." No idea where you pulled this from, but we do this pretty much every day. Knocking out the homologous gene in the model animal and replacing it with the human gene is necessary to validate that the two genes (model animal and human genes) perform the same function. It's called a "rescue" experiment and no journal will accept your paper (if it's on a gene) if you haven't performed this experiment