When Kate started hollering that Madeleine had been taken there is no way that either she or Gerry would have been able to control events thereafter. They would have no way of knowing how their friends would react, what they would do, which direction they would run to search, who would go to fetch the police or staff members, they would have no way of knowing if there was a police patrol in the streets nearby, or whether CCTV covered any of the areas in town between the Ocean Club and the sea front, or who was out and about that evening strolling to and from a pub or restaurant, they would have had no way of knowing that their faces would be plastered across the world's press the very next day so that anyone who had seen them up to no good would have immediately identified them, they would have not been able to control any of that.
So to suggest that the most logical course of action in order to dispose of a dead body in a tourist town is to relinquish ALL control of the situation by waiting until AFTER raising the alarm and drawing attention to yourselves BEFORE hiding the body, and then PARADING that body through the very heart of that tourist town is completely and utterly absurd. But some people seem to think this is what actually occurred that a) the McCanns were really really stupid and b) the McCanns were really really lucky to have gotten away with the dumbest cover up plan ever concocted.