Not sure about that.
1) He may simply have stated that he did not wish to be interviewed on camera.
2) He may not allowed have allowed to be, in view of his former career.
3) He seems to have written up the report on behalf of Oakley, for which there is a confidentiality clause.
What would appear to be a standard clause doesn't appear to have stopped any of them from airing their views. If that had been illegal, then presumably the overseeing legal adviser for the documentary would have stepped in.
Carana ... it was stated, unequivically, that Exton was 'legally bound' not to discuss his investigation publicly
How that can cause you confusion is beyond me
And that 'clause' you keep refering to ( although no such clause has ever been mentioned ) certainly did
not "stop any of them from airing their views"
Nice Major Tim, who was working
for Henri Exton, was permitted to air his views extensively ( including his sympathy for the McCanns )
Exton, though, was gagged for some reason