My memories of that Tour are a little hazy, but nevertheless, what a great idea for a thread!
I think that Sastre was about a minute behind Schleck, approaching Alp duez. Evans was roughly equal in the standings with Sastre, but was seen as the favourite for the Tour overall, given his greater reputation in the ITT, of which there was still a long one to go on the penultimate day.
I don't see Sastre attacking on that climb, and being allowed (?) to attack, being based on any team orders. I think that CSC knew that they had two cards to play, and took the situation on its merits. If Carlos had struggled to gain much time on the other contenders, then that would have confused matters with the yellow jersey, however, since he quickly extended his advantage to over a minute on Evans on the road, it made sense for the Schleck brothers to more or less ride as a distraction, and to help Sastre gain as much time as possible, as it would be likely he would outperform Schleck in the ITT anyway.
Once Carlos had established a significant gap, it made no sense Andy working for Frank, unless in the process they could have dropped Cadel, which never appeared likely.
Frank Schleck also never appeared to have the 'winning is everything' attitude of some other riders either. He always seemed very happy for his brothers - greater - successes, and once he did get onto the Tour podium in 2011, seemed very satisfied with that (a little bit like when Valverde did). For a number of years he was one of the very best climbers in cycling, and possibly could have won a giro or vuelta if he had made it a target, but he was happy doing what he did.