Clearly Carlos Pinto de Abreu was concerned that Kate McCann would incriminate herself after he was briefed on the evidence held by the police. The safe option?
Personally, I've never heard of a mother of a missing child needing a 'safe option', if she was innocent she had nothing to fear.
He saw something we have never seen; Kate McCann under pressure. According to Fiona Payne she could be volatile;
Kate's very reactive, you know, she's, she's a completely different personality and, you know, if she's angry she'll show she's angry and when she's upset she'll show she's upset,
Gerry was more controlled;
Gerry can be, erm, he's more able to, to sort of see through all that and just think, hang on what's right for, what's right, what's going to get us further forward here, you know, getting upset and screaming at the Police isn't going to get us anywhere and he's always sort of pulling Kate back a bit really and saying, 'Look, that that's not going to help, we've got to do this',
http://www.mccannpjfiles.co.uk/PJ/FIONA-PAYNE-ROGATORY.htm