Do you think the PJ are surprised that SY have got nowhere following other leads? At least they've eliminated a lot and maybe that was the point until one remains.
I am certain that Scotland Yard have been working to full capacity on Madeleine McCann's case. I am delighted that you recognise the vast elimination programme they have had to pursue in that process. Resulting in, as we know from Portuguese sources, their interest in a man who carried out a burglary in the resort at noon on the day Madeleine disappeared.
That would appear to be their present line of inquiry ... stranger abduction with an apparently known criminal who may or may not know other criminals working the resort at the same time he was.
Quite obviously SY cannot take the initiative to do anything regarding this Portuguese National until all the formalities have been met ... which as we know can take a considerable amount of time.
So maybe the Policia Judiciaria are less surprised about anything impeding SY progress than you might give them credit for.