This article completely misses the point. It wasn't a sudden lapse of professionalism that caused the nurse's reaction. It was fear. When someone that belligerent, physically intimidating, and armed, shows himself to be so devoid of reason and rationality, Christ knows what else he might do. His intentions can't be trusted, and fear is a completely justifiable response, especially in today's law enforcement climate.

That said, it's true that you can't resist unlawful arrest. You just have to, in the heat of the moment, suppress any instinct for self-preservation and put your trust in the will of a psycho. Easy enough, right?