Short sharp repetitive attacks would only break up Sky's train in the tour if they tried to follow and react, they didn't do that if you watched it. When Cadel, Nibs, TJ or JVDB attacked they often let them go, just reeling them in through a high pace, patiently.
ACs attacks yesterday were great to watch but on big ascents in the tour, he would have had to burn a serious amount of energy to drop the Sky train for good doing that. Wiggins was no coward, he simply rode to his strengths as any athelete should do.