I think he hits it on the head when he asks:
Would you stay in bed because there was no reason to get up? What about when you finally got hungry and stumbled into the kitchen - what would you do after you were done eating?
That would be Stage One of the disorder - walking in a daze. (Probably modified because I live at home, but I could pass it off as depression to my family.)
Presumably, though, I would eventually get stir-crazy and get out of this house. I would stand by a busy street and think about playing in traffic, but the horror of making people suffer through having hit someone, the horror of having to pick up another broken body off the street, would discourage me.
I'd turn and run down the street. I'd stumble to a walk a couple hundred meters away. I'd turn and jump a fence into someone's back yard, and begin a trespassing spree, cutting through backyards and crossing streets on a random vector. I'd go trying to do some nutso stunt like wall-jumping, and then try to refuse medical assistance when I cracked my fool head open, and then admit to having health insurance once I'd been forced into the ambulance. I'd ask to have no-one told I'm in the hospital, but they'd probably be told anyway. I'd try to escape out the window. I'd try to talk passing interns into unstrapping me from the hospital bed. I'd think about making a suicide attempt, and realize that I'm attempting memetic quarantine - attempting to make it a secret that nothing matters. I'd try to justify it to myself, and probably succeed via the same revulsion that kept me from throwing myself under buses.
I'd switch to the second alternative - attempting to convince people I was sane. I would fail miserably, of course. In the meantime, though, I'd take up projects, like the IF writing I'm not doing right now, or maybe trolling on philosophical/religious forums. And I don't see where it'd go after that.
Of course, in reality, the odds that something like that would happen are remote. If morality were as easily crushed as that, it wouldn't still be here.