A lot of hospital have armed tactical teams. Though I would guess that in major metro areas they would be more hidden, and so less used.
If they mean explicitly stationed armed and vested police officers in level 1 trauma centers, absolutely.
Personally, I'm in favor. An ED deals with a lot of situations that would normally be met with force by law enforcement, every average Tuesday.
Having someone who's trained and comfortable with hospital procedures, staff, and "normal" there can mean avoiding prematurely escalating a confrontation and knowing when to immediately escalate to prevent injury or loss of life.