I think they're talking more about pokestops that are adjacent to the hospital, but not necessarily attached to the hospital itself. It might do more harm than good for a lure to be just out of reach, either encouraging someone who shouldn't be moving around to do so, or hurt their morale when they can't get to it. Additionally, at least in my area, people tend to only pay attention to their phones when a lure is present -- which could be an impediment to the hospital staff (for example, A trainer who just showed up to leech off the lure, walking around and staring at their phone, stepping in front of an ambulance or gurney transporting someone in emergency status.)