What protocols are they exactly? Do you think they include "The police forces of all European countries should guard those waiting to be interviewed by the police in case anyone tries to speak to them."
A few people spoke to the McCanns that morning; Steve Carpenter, the lady from block 6 and Robert Murat, for example. Should they all have been shooed away?
In answer to your query - yes, they should have been 'shooed' away and all approaches made via the police if necessary.
Did Steve Carpenter, the lady from block 6 and Robert Murat use invasive interrogation?
Did they add to the stress and trauma already being suffered?
Steve was known to Kate and Gerry.
He introduced them to Murat who had offered his assistance which was to come back and haunt him.
Murat translated a description of Madeleine for the GNR on their request so his presence at least proved useful but the approach should have been made via the police and not directly.
In response to your first sentence ... common courtesy should dictate victims of crime should not be left to their own devices to be accessible to any passing stranger ... and normal police procedure should ensure their security which was obviously lacking that morning in Luz.
If you want to look for a protocol which says different ... be my guest.