Even if he cracks completely, it was totally worth it.
If he just sat on and they messed about like on Plateau de Beille, they'd have lost the race to Evans, and everyone would have (justifiedly) called them idiots for not trying something.
If he loses the race from here on in, people will remember his heroic ride, people will remember that Andy Schleck left everything on the slopes of Izoard and Galibier, and he's not a figure of fun, he's a guy who fought with everything he could but just didn't have it.
Our biggest problem with the Tour de France in recent years is that riders have been too afraid of losing their positions and blowing up in future stages to risk anything, and it's led to formulaic, dull racing. Óscar Freire says "to win, you must first be prepared to lose". Too many people at the Tour have forgotten that. It's often felt like Andy Schleck has forgotten it. Today, Óscar's sound advice played through his head.
If he sat on or messed about à la Plateau de Beille, he would lose the race. If he attacked and took everybody on from 60km out, he might still lose - but he might win too.