Goof? or Laziness?? Why didn't his hair grow back?
Remember in an earlier scene, when he was describing to her how his illness came about... he would shave and it would grow back so quickly it was pointless to keep it up...
Later on when he's dying, he wants her to shave him -- all of him. He stays relatively clean shaven until he goes into the water... with the exception of a 5:00 shadow right before he dives in.
You're laborers, you're supposed to be laboring! That's what you get for not having an education!!