Yay food crisis solved too!Now I'm afraid they'll make fruit salad.
OR.... could they? Imagine momotarou digging that hole himself under the guise of 'training his muscles and his foot stances'. Once he dug deep enough, the old couple turned on him and attacked him with shovels. By that time, momotarou would've been exhausted and being inside the hole would make it even harder to defend or counterattack. Chances are, momotarou didn't even realized he had been hit in the head. Look, his sword is still sheated down there, the exhaustion from digging a hole all day coupled with a sudden blunt trauma to the head must've got him....I feel like a lot of people are missing the fact that there's a 99% chance he did this willingly.
His old parents couldn't possibly have overpowered him, and if he didn't do this there would be no stoping the Oni.