In my opinion he wanted to explain why he thought OG should have carried out the first task necessary when a child disappears; elimination or implication of those closest to her. Asking the questions themselves and in English would have been necessary, in his opinion, to achieve that.
"I do though think that a point worthy of reinforcing is that a proper, conclusive and reasoned elimination or implication of Kate and Gerry McCann would have been in everyone's interest, most of all theirs. That would have been my first objective had I been leading Operation Grange and so that is the biggest issue I have with how that investigation proceeded. To eliminate or implicate those closest to the child in this type of case is not only the documented best investigative practice but is common sense. Had Grange done this then everything would be a lot clearer. I have no idea why this was not done but I am satisfied on what has been said by the Met and what is available that it was not."
http://colinsutton.blogspot.com/
In my opinion that was a task for the Policia Judiciaria to carry out initially. In the intervening period the McCanns had been made suspects and had been thoroughly investigated as was Robert Murat and nothing could be found to link any of them to Amaral's theories.
Amaral's theories which formed the basis of suspicion against the McCanns were all categorically disproved by the PJ.
It isn't possible to wind back time and erase all that happened since Madeleine's disappearance until the opening of the English investigation as though that was the starting point.
It wasn't the starting point or anything like it and neither Sutton or anyone else knows what happened between witnesses and the Scotland Yard investigators.
For example no-one heard of Dr Totman until the media found out who he was ... but he was interviewed. People who had suffered sexual assault by an intruder as children were also interviewed.
Quite simply we do not know who else was and I for one would be astounded if it started and stopped with Dr Totman and those assaulted as children.