Having thought about it, I'm not sure I agree.
We know that the McCanns were (in certain quarters!) irrationally excoriated for "fleeing from justice" leaving Portugal when they did. Had they left earlier, they'd have been excoriated all the more fiercely.
Never forget that Mark Harrison (thank goodness!) was only ever interested in solving the mystery of what happened to Madeleine; and recommended bringing in the dogs because he saw them as a valuable tool to contributing to that end. I'm certain he'd have recommended bringing them in whether the McCanns were there or not.
I think Grime would have pursued his separate agenda come what may; and all bar two of the inspections (at the villa and at the gym, because there would have been no clothes to inspect) would have gone ahead.
Remember that Harrison only ever recommended inspection of all vehicles owned or driven by Murat and I'm pretty certain he'd still have made the same recommendation.
Harrison also only ever recommended inspections in places where Madeleine either had been or conceivably might have been.
Aside from an askew reference where Harrison appears to touch his forelock and take orders from others (unspecified) about inspections in places Madeleine never lived in or went near, Harrison had nothing to do with those inspections, and conspicuously omitted reference to UK involvement in them in his summary of all searches. So a search at the villa never figured in Harrison's plans; neither of any vehicle other than those driven or owned by Murat.
I think it likely that 7 of the 8 cars besides those belonging to Murat (excluding the Renault scenic) would still have made it in, perhaps with zero result.
I think there would still have been a thrust and emphasis towards implicating the McCanns with the added propaganda of them fleeing from justice thrown in ...
I think that if the finger of suspicion had not fallen on Madeleine’s parents it is highly likely that Robert Murat would have had the full force of the investigation directed at him and I think it is possible he could have found himself in serious trouble.
Being made an arguido so early in the inquiry possibly gave him legal rights which helped him to avoid this outcome.
I think even very early on there were efforts underway to pin the crime on any feasible person … to ensure the true perpetrator\s remained in the clear.
All it would have taken imo would have been for Jane Tanner to identify the man she saw as Robert Murat. I think he was very fortunate that she was so steadfast in refusing to identify a man she had not really seen, because at that time I think the PJ believed it was him.
A positive identification would have been all they needed to intensify their scrutiny to get this case solved.
I think he was being ‘set up’ with the anonymous phone call 8th May being the first move to implicate him.
On the11th May I think the PJ really thought they were on to something when the site visit suggested that the direction taken by the man seen by Jane Tanner and the proximity to the Murat villa and a named suspect tied in so well with their theory of abduction.
Suspicions of Inspector Pedro Varanda following the Diane Webster interview which Murat translated in combination with the suspicions of Chief Inspector Reis Santos ... compounded by the suspicions he raised in the British journalist would perhaps have given him a lot of trouble if the focus had remained on him.
http://www.mccannpjfiles.co.uk/PJ/ROBERT-MURAT.htmI have read carefully what you have said but I still think if the McCanns had returned home in despair at an earlier stage in the proceedings, if Jane had mistakenly identified him and other witness statements had been taken into account, I think Robert Murat would have found himself between a rock and a hard place ... leaving the perpetrator to roam free without a care in the world because everyone would have given up on Madeleine.
I think that is why Madeleine’s parents have suffered so much abuse, because they refused to go home and let go as 99.9% of the population would have ... they refused to give up on Madeleine ... no-one is looking at the original arguidos ... but two law enforcement agencies are looking for the perpetrator\s.