I agree.
It was, however, a diligence that should have been carried out and wasn't. Therefore the PJ were within their rights to request it. For them, the outcome was perhaps less important than the 'dotting of i's and crossing of t's' prior to archiving the case.
The refusals to attend by the witnesses handed the moral high ground to the Portuguese authorities. They were willing to keep on investigating.The friends and acquaintances of the McCanns were unwilling to cooperate with them.
If the diligence should already have been carried out, why wasn't it? Why did it have to wait until Rebelo took over from Amaral?
Rebelo was carrying out procedures as we would know them when he took over the case, probably in my opinion to give
him a better understanding of the situation.
The high moral ground was in my opinion lost to Portugal when procedures such as the reconstitution were neglected by the police and when material witnesses were so terrified of their position that they consulted lawyers about the advisability of returning to Portugal.