It is definitely legal and in many places customary for nurses to push induction meds. ICU and ED settings come to mind as common examples. It's probably a surgicenter policy/bylaw there that the nurse is not allowed to push certain meds at that facility. That having been said, it is completely inappropriate and extremely dangerous for the charge nurse to barge in and demand the OR Nurse stop pushing meds immediately half way through a high risk induction. This should have been something discussed after the fact, not during. She could have spoken to the involved parties and even submitted an incident report or whatever their equivalent is... afterward. This was a perfect example of a nurse being more concerned about being "by the book" than about what is actually best for the patient in the moment. In that moment the nurse was more concerned about being technically right than morally right. She had plenty of opportunity to bring down the compliance hammer after the fact, but she could have done it without endangering the patient in the moment.
Although I think the charge nurse was way out of line, I don't think the anesthesiologist has much of a case here. The courts don't really understand what is safe and what isn't and wont be able to wrap their heads around the danger the patient was exposed to. They will simply look at what the official policies actually were and who was violating the policies and who wasn't. Was the nurse technically allowed to push those meds? No? Ok so anesthesiologist is in the wrong, case dismissed. They won't really see the bigger picture of the patient endangerment that occurred due to the ill conceived timing of the interruption.