Kate's experience is that she refused to answer police questions about it. Amaral wouldn't need to comment on whooshing curtains because he concludes that Kate opened the window 
Are you aware that in not answering the questions you are jeopardising the investigation, which seeks to discover what happened to your daughter?
Kate McCann: ‘Yes, if that’s what the investigation thinks.’
You do know that the PJ were not asking any questions at that stage of the proceedings four months down the line which would further the investigation into Madeleine's disappearance.
They had already written Madeleine off as dead by then without a scrap of supporting evidence.
The investigation you are talking about was now centred on the already tried and tested rule of thumb that the mother 'dunnit'. Only this time the rule of law prevailed with the accused having access to a lawyer during questioning whose advice was not to answer questions.
What is it you find extraordinary about a person refusing to answer questions in the full knowledge that to do so would be assisting the PJ in their totally wrong investigation into the wrong case.
The PJ
were not investigating what had happened to Madeleine the only investigation they were interested in was investigating Kate.