This is my earlier reply to a similar question concerning hijackers' lap dances and drinking:
While this kind of behaviour seems rather suspicious, a deeper look reveals that terrorists do not always act like one would expect.
Different sources report the following:
“Ziad Jarrah came from a secular Muslim family that was easygoing -- the men drank whiskey and the women wore short skirts about town and bikinis at the beach.”
“Khalid Shaikh Mohammed was a frequent visitor to Manila's red light district, including its karaoke bars and mirrored go-go clubs, where he introduced himself to women as a wealthy businessman from Qatar.”
“They must have assumed that the purifying nature of their approaching martyrdom gave them some sort of cosmic dispensation.”
"Their sense of dispensation was derived directly from the idea that they were engaged in jihad (holy struggle). Now you know, in jihad there are certain liberties allowed. I believe they took the liberty of making their own interpretation of these dispensations or liberties granted to the one making jihad."
It would seem, that so-called errant western behaviour does not exclusively mean that you cannot be a terrorist at the same time. Their suicide mission might be interpreted as a purifying event, making their earlier behaviour less damaging. And you have to keep in mind, that Islamic Law condemns the killing of innocent civilians. They were not following the strict rules of their religion there either.