Whenever i die while in jail, i get sent back to my spawn, i can move around but i can't access anything and i get sent back sometimes if i try to open a door.
Im pretty sure i shouldn't be able to do this, so i just wanted to point it out to you.
Can't you change whether or not people die from hunger? If so, just set it to like .5 hearts left at maximum hunger damage. Or we could have fun, throwing eggs at prisoners actually is required and encouraged, seeing as it helps them to survive.