I don’t think he’s been sentenced yet. As well as the inevitable skull fractures, the baby had bite marks. Difficult to see how she acquired those from a spin in the dryer.
She didn't, there were further assaults on subsequent occasions. The mother witnessed the dryer incident, yet left her child with that scumbag on two further occasions.
The "mother" in the OP is vile. As is everyone who saw what she was doing and didn't act to protect that poor wee soul.
She'll have to live with it aye, but she took that chance from her boy. He doesn't get to live with anything, because he's dead.