If they're anything like me, it's not "desperation" to get into YC, necessarily, as much as the ridiculous hatred of failure. They'd probably go equally nuts for anywhere they applied, be it Harvard or Juliar or for unemployment checks.
I got the impression that mrkurt was implying the Grubwithus founders didn't want to fail the YC interview, not that getting into YC guaranteed Grubwithus would be successful.