[And the doctor was actually looking at them. It was a dissecting look and oh dear maybe it was time to try some logic.]

Doctor, while I am sure that an ethical argument will not work on you...

[Because let's face it, they wouldn't even be on this job if this man had known what ethics were.]

...I would appeal to your sense of pragmatism. The man you are going to experiment on, clearly he will not handle it. It's a waste of your mana to do so. And I suspect you have tried this exact same method multiple times. So why do something so pointless?