Nope, if you're helpless, they just outright kill you if they choose to.
And how would you square this with that's written on page 7 of the GM's Guide?
"As GM, you should basically never kill a defenseless player character."
You should probably read the entire paragraph (or chapter even). As a GM you shouldn't just kill a defenseless PC, but the player wasn't defenseless when he tried to kill the monster (just before he become broken and defenseless). The GM should play the monsters. Should a monster not eat just because that page 7 had said something. That chapter is a guideline how to GM this game, but if a player is in a battle with a monster he know the risks. It would be a very strange game, if the player could stand there and say "it is ok for me to become broken because in our game, the GM doesn't kill defenseless PCs".
Then, playing the monster here, unless the monster is big enough to swallow a human whole, the monster would probably try to grab the defenseless PC and escape with him, so he (or she) could eat the PC later in his (her) lair.