It’s a mouse. If you think feeding one to a snake is ethical, then it’s a little strange this would be unethical. At least the human has the mouse’s wellbeing at heart.

The term "lab rats" exists for a reason. This is in the bottom 10% of weird shit people do to animals for research.

Is it more ethical to systematically shoot cows in the head, have 2000 chickens share a 500sqft enclosure, have pigs raped to create offspring, etc?

The amount of cruelty humans inflict on other animals has very little bounds, this is fairly benign in the big picture honestly.

If we can even have robots that can perform critical surgeries with total precision and save more lives would that be bad?

That ship sailed a long time ago. Science decided that killing mice for experiments (regardless of the experiment) is fine. In fact, a large amount of the mice killed are just redundant (not needed for a particular experiment)

Oh don't worry, they made sure to have a human acting as an accountability crumple zone: "A licensed vet gated every irreversible step and held a physical kill switch to stop the AI agent."

(/s)