It depends on the intention, surely? You have no evidence that Silvia Batista intended any offence when she said what she said. In my opinion we know exactly what Kate McCann's intentions were; to convince her audience of her innocence and of the ineptitude of the Portuguese police.
This man did not deserve my respect. ‘F*****g t****r . .[madeleine]
Silvia Bastista, probably didn't intend any offence, it was Amaral who made a big thing of it, putting it in his documentary and if to say 'look at these strange people'.
I think Kate wanted to show how she was bullied, Ricardo was telling Kate that blood had been found by the dogs and that the DNA matched Madeleine's, and asking her to explain it. In fact all that was a lie wasn't it? Kate was no doubt shocked by the revelation, wondering whether Madeleine was dead, and also shocked that they thought she was responsible. I am sure in the circumstances chanting what she did under her breath as she said to get her through the ordeal as it somehow give her strength and helped her to take charge, was quite in my opinion acceptable.