There are a very limited number of people who can actually help to locate Madeleine. Unfortunately, no one knows who they are, and they probably don't know themselves. So it is necessary to keep the profile of Madeleine high in the minds of everyone. This is what The McCanns seek to do.
But if people think that she is dead then some people simply won't bother to even think about anything that might be suspicious.
There is no doubt that the word of the PJ Inspector who coordinated the case will have been taken into account as more reliable than most, which is one of the reasons for why his word had to be challenged.
He was also becoming more vociferous as the months went by.
Personally, I believe that if he had stopped with his book then The McCanns would have let it go by. It was the video and the numerous interviews that made it obvious to anyone that he was just going to go on and on with even more explicit theories., which have fuelled the most appalling Internet campaign against The McCanns, and consequently Madeleine.
I have no idea what will become of The Libel Trial, but one must remember that this was instituted some considerable time ago when Amaral was at his worst in defaming The McCanns. No Police Officer ex or otherwise should be allowed to do this when he has absolutely no proof.