No, they show up because this is a mandatory tournament.
Nadal skipped it citing injury. Federer skipped it because he's allowed to by the rules given his age and number of matchs on tour.
They'd get a 0 pointer if they withdrew with no valid reason.
If you were reading along, I mentioned it was mandatory earlier in the thread. Duh. But Murray didn't have a knee injury before the tournament either, so he'd also get 0 pointer for withdrawing. I don't get why you responded with this to me. I wasn't the one arguing he was stupid for not skipping the tournament, Chaz was.