You agree to help a friend in a surgical operation where your heart will be used to pump her blood while her heart is being operated on. Midway through the surgery, you get a craving for donuts and decide to leave to get some from the nearby donut shop, causing your friend to die. A bodily autonomy absolutist would think this is your right, and that the doctors have no right to make you stay, which is obviously absurd

this is somehow more ridiculous than the standard violinist example. you'd be unconscious. if you somehow sleepwalked to get the donuts you wouldn't get tried for murder.