There is a trauma surgeon in the article stating she shouldn't have even been allowed in the room, let alone allowed to drill into a patient's skull.
Is it less ethical or more ethical if the patient had given informed consent?
No patient gives consent to who is helping in the surgery because there is an implicit understanding that it will only be performed by qualified licensed personnel. There are multiple regulating bodies that prevent unqualified people from practicing in a professional setting. So, it is not unreasonable to make this assumption.
My argument is that it would be one thing if this was a simple superficial elective surgery where the patient consented to allowing the doctor's unqualified child "to give it a go" popping a pimple or something. It is significantly worse because it was a life-threatening emergency procedure where the doctor elected to increase the likelihood of failure/harm/death while the patient was in a position where they couldn't consent to the doctor taking that unnecessary risk.
If the gun was plastic, the barrel would definitely be the hottest part of the gun. Would still be true if the gun was a lighter metal, I think. Hmmm