Nurses not a threat to Mob guys.
Also, Mac needed to have an official hospital person legitimize his removal of the Corleone guards. She said, "Your father had too many visitors."
True TB, but she could have been a witness to the murder or murder attempt. If he was able to rid the hospital, apparently, of just about everybody, then he could have found someone to authoritatively legitimize his removal of the guards. Besides, I think her statement that the guards interfered with hospital routine sounded weak.
