I don't think he did either. However, I find it rather pathetic to say that by attacking Nibali he, Contador, was "actually showing him respect."

This only adds baseness to his vile act, by trying to take us all for morons.
What utter BS. The dignified and classy thing to have done would have been, at 1.5 k out, since he did no work previously and he didn't have a teammate up the road to take over; to up the pace and even ferociously, yes, but steadily. At that point Nibali would have had nothing but his own legs to respond with, without having felt slighted for having witnessed the breaking of a deal any class act would have quite naturally felt was binding. Perhaps this way Alberto may not have gained the 6 seconds extra or whatever it was, though this wouldn't make or break his Giro.
Anton would have been reeled back some just the same, however, and, to top it all off, Contador would have affirmed his undoubted nobility of strength and talent, while also demonstrating being a class act before a colleague who busted his a$$ over the last ks of the climb to the Spaniards convenience. Indurain would have handled it thusly.
The way Alberto rather chose to handle the situation, was, in my book, simply weak and unsportsmanlike.