What do you mean by "they don't want"? Do you mean now, in 2013, or back in 2008?
Amaral could have organised it in the days following the disappearance in May 2007... but didn't.
Even if the purpose of conducting a reconstruction back in May 2007 (in the PT system) was to check out the T9 as opposed to appealing for information, it could have been explained to the press.
By 2008, with all the lurid headlines, I'm not really surprised that they were wondering what this was all about.
Aside from the initial panic interviews given by family members back in the UK, when have the T9 been "vocal" concerning the PT cops?
Why should an action by the PJ as part of an investigation need or requirement, concerning the last witnesses to see Madeleine alive and well, be explained to the press?
Since when do police investigations in any country explain each action or diligence to the press in advance?
Not only should witnessess NOT have the reason why the investigation needed a reconstruction explaining to them (for obvious reasons) but in fact the PJ went out of their way and did provide an explanation by email to all of them.
And isn't it convenient that the Mccann's agreed to take part by email after it was clear the other members of their group refused making it a certainty that it would not happen, irrespective of the Mccann's attendance?
Quite a clever move on their part, as they can claim they were going to attend but others werent, so it wasn't their fault, they were happy to do it.
Unfortunately Mitchell let the cat of the bag in that article saying their lawyers would block it anyway.