"You wouldn't have boned anyone anyway, Captain Lean-to."
And it wasn't just the patients who sometimes got accidental pro bono operations. While extremely skilled, Liston's knife hand was kind of like a giant twister made of hacksaws. So even standing too close while he operated could be a literally life-threatening endeavor.
Liston's most famous case perfectly demonstrated both his amazing surgical speed and his total disregard of what was going around him: an operation in which he actually managed an impossible 300% mortality rate. In a frantic two and a half minutes, he amputated the patient's leg and the fingers of his assistant, and he slashed the coattails of a bystander. The patient and the assistant died of gangrene in the hospital later, and the bystander died of fright, because apparently people had the constitutions of fainting goats back then.
But that's OK, because Liston also created this handy Silent Hill-style restraint.
Liston's reign as surgeon supreme was finally ended by the arrival of working anesthetics, which rendered his lightning surgery unnecessary. So he gave up the slasher film method of operation and pioneered the use of anesthetics instead.
Begrudgingly, we assume.