I'm sure you see the connection. Although you may not agreed that her inability to (in this situation) plan appropriately or work though unfamiliar problems under stress necessarily apply to her vocational abilities as well.

Personally, I don't know the woman so I have absolutely no idea whether she's a competent nurse or not. She may be a great nurse but was operating far outside her area of expertise and failed to recognize it.

I will agree that this event is not de facto evidence that her nursing abilities are below par. However, if this event were the only thing I knew about the woman and she was going to be my nurse, I would at least have a little question mark next to her name in my mind.